v0.4.68: fix NFS secure-export mount, logo cache-bust, dashboard disk card, NFS form spacing

Four operator-reported issues from v0.4.67 validation.

## 1. NFS MNT3ERR_ACCES even with the host IP allow-listed

Root cause: Linux kernel nfsd (what UniFi UNAS / Synology / TrueNAS all
run underneath) exports with the `secure` option by default, which only
accepts mount/NFS requests from a privileged source port (<1024). v0.4.67
explicitly connected from a non-privileged port on the mistaken assumption
that uid 10001 can't bind low ports — but the binary carries
CAP_NET_BIND_SERVICE (granted via setcap for the DHCP/TFTP/HTTP low-port
binds), which also covers privileged *source* ports for outbound connects.

Fix: build_connection now tries a privileged source port first (the common
case for every appliance NAS), then falls back to a non-privileged port
for `insecure` exports or capability-less environments. Each attempt has
its own connect timeout; a timeout on the first attempt skips the fallback
(the server isn't answering — a retry would just double the wait).

Also: hint_for now recognizes MNT3ERR_ACCES distinctly from NFS3ERR_ACCES
and explains both the allow-list and the secure/insecure angle, with the
UniFi /var/nfs/shared/<share> path convention called out.

## 2. Custom logo didn't update the top-left brand mark

The brand <img> and favicon were pinned to ?v=<app-version>, which only
changes on upgrade — so uploading a new logo left the cached bundled SVG
in place. Added a monotonic `rev` counter to BrandingStore that bumps on
every set/clear, persisted across restarts, surfaced through index_html as
an extra &r=<rev> cache-bust token on the brand mark + favicon URLs. Since
index.html is served no-cache, the fresh token lands on the next reload
after upload and the new logo appears immediately.

(Note: this updates the WebUI brand mark. The PXE *boot menu* still shows
the ASCII wordmark — painting the operator's PNG there needs the
IMAGE_PNG-enabled iPXE rebuild that remains queued for native x86_64
hardware. The /branding/pxe-logo compositor is ready for when it lands.)

## 3. Disk-space card on the Dashboard

Extracted the Storage tab's disk card into a shared diskSpaceCard(disk)
helper and added it to the Dashboard grid under the stat strip. Dashboard
fetches /api/storage/disk with the same graceful-degradation fallback the
Storage tab uses.

## 4. NFS "Add share" button touching the form field

The NFS card has a single form row (vs SMB's two), so the button butted
right against it. Added margin-top:14px to match SMB's effective spacing.

Tests: 162 passing (+2 — logo_rev bump, MNT3ERR_ACCES hint). clippy clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

crates/webui/src/app.js

@@ -116,6 +116,46 @@
     return root;
   }
 
+  // Disk-space card. Free + used + total for the volume hosting the ISO
+  // directory, with a coloured bar. Warns at 80% and goes red at 95% so
+  // the operator sees the runway shrinking before uploads start failing
+  // with ENOSPC. Shared by the Storage tab and the Dashboard (v0.4.68).
+  function diskSpaceCard(disk) {
+    const total = Number(disk.total_bytes || 0);
+    const avail = Number(disk.available_bytes || 0);
+    const used  = Number(disk.used_bytes  || 0);
+    const pctUsed = total > 0 ? (used / total) * 100 : 0;
+    let barClass = 'diskbar';
+    if (pctUsed >= 95)      barClass += ' full';
+    else if (pctUsed >= 80) barClass += ' warn';
+    return el('div', {class:'card'}, [
+      el('header', {}, [
+        el('h2', {}, 'Disk space'),
+        el('span', {class:'sub'},
+          total > 0 ? (pctUsed.toFixed(1) + '% used') : 'unavailable'),
+      ]),
+      el('div', {class:'body'}, [
+        el('div', {style:'color:var(--fg-dim);font-size:12px;word-break:break-all'},
+          disk.path ? ('Volume: ' + disk.path) : 'Volume path unknown'),
+        el('div', {class: barClass},
+          el('div', {class:'fill',
+            style:'width:' + Math.min(100, pctUsed).toFixed(1) + '%'})),
+        el('div', {class:'disk-meta'}, [
+          el('span', {}, ['Used ',  el('strong', {}, fmtBytes(used))]),
+          el('span', {}, ['Free ',  el('strong', {}, fmtBytes(avail))]),
+          el('span', {}, ['Total ', el('strong', {}, fmtBytes(total))]),
+        ]),
+        pctUsed >= 95
+          ? el('p', {class:'msg err', style:'margin-top:10px'},
+              '⚠ Less than 5% free. Remove old ISOs or grow the volume before uploading more.')
+          : (pctUsed >= 80
+              ? el('p', {class:'msg', style:'color:var(--warn);margin-top:10px'},
+                  'Volume is getting full. Consider pruning old ISOs.')
+              : null),
+      ]),
+    ]);
+  }
+
   // Categorize an ISO row's "bootable now" status — drives the amber
   // tint borrowed from Bootimus v0.1.62. Returns {ok, reason}.
   function bootability(iso, settings) {
@@ -142,6 +182,13 @@
       const isos = await getJSON('/api/isos');
       const clients = (await getJSON('/api/clients')).clients || [];
       const entries = (await getJSON('/api/queue')).entries || [];
+      // v0.4.68: surface the same disk-space card the Storage tab shows,
+      // so operators see capacity at a glance from the landing page.
+      // Tolerate the endpoint being unavailable (e.g. statvfs failure)
+      // the same way the Storage tab does.
+      const disk = await getJSON('/api/storage/disk').catch(() => ({
+        total_bytes: 0, available_bytes: 0, used_bytes: 0, path: '?',
+      }));
 
       const ipxeOk = (status.ipxe_assets || []).length > 0;
       const stats = el('div', {class: 'statstrip'}, [
@@ -222,7 +269,7 @@
             '⚠ ' + i.filename + ' — ' + b.reason)))
       ]) : null;
 
-      return el('div', {class:'grid'}, [stats, recentBlock, problemsBlock].filter(Boolean));
+      return el('div', {class:'grid'}, [stats, diskSpaceCard(disk), recentBlock, problemsBlock].filter(Boolean));
     },
 
     network: async () => {
@@ -737,7 +784,7 @@
       const nfsMsg = el('div', {class:'msg'});
       const nfsServerIn = el('input', {type:'text', placeholder:'10.0.0.5'});
       const nfsExportIn = el('input', {type:'text', placeholder:'/srv/isos'});
-      const addNfs = el('button', {onclick: async () => {
+      const addNfs = el('button', {style:'margin-top:14px', onclick: async () => {
         if (!nfsServerIn.value || !nfsExportIn.value) {
           nfsMsg.replaceChildren(document.createTextNode('Server and export are required.'));
           nfsMsg.className = 'msg err'; return;
@@ -794,45 +841,7 @@
         el('span'),
       ])) : [el('div', {class:'empty'}, 'No NFS shares configured.')];
 
-      // Disk-space card. Free + used + total for the volume hosting the
-      // ISO directory, with a coloured bar. Warns at 80% and goes red at
-      // 95% so the operator sees the runway shrinking before uploads
-      // start failing with ENOSPC.
-      const total = Number(disk.total_bytes || 0);
-      const avail = Number(disk.available_bytes || 0);
-      const used  = Number(disk.used_bytes  || 0);
-      const pctUsed = total > 0 ? (used / total) * 100 : 0;
-      let barClass = 'diskbar';
-      if (pctUsed >= 95)      barClass += ' full';
-      else if (pctUsed >= 80) barClass += ' warn';
-      const diskCard = el('div', {class:'card'}, [
-        el('header', {}, [
-          el('h2', {}, 'Disk space'),
-          el('span', {class:'sub'},
-            total > 0
-              ? (pctUsed.toFixed(1) + '% used')
-              : 'unavailable'),
-        ]),
-        el('div', {class:'body'}, [
-          el('div', {style:'color:var(--fg-dim);font-size:12px;word-break:break-all'},
-            disk.path ? ('Volume: ' + disk.path) : 'Volume path unknown'),
-          el('div', {class: barClass},
-            el('div', {class:'fill',
-              style:'width:' + Math.min(100, pctUsed).toFixed(1) + '%'})),
-          el('div', {class:'disk-meta'}, [
-            el('span', {}, ['Used ',  el('strong', {}, fmtBytes(used))]),
-            el('span', {}, ['Free ',  el('strong', {}, fmtBytes(avail))]),
-            el('span', {}, ['Total ', el('strong', {}, fmtBytes(total))]),
-          ]),
-          pctUsed >= 95
-            ? el('p', {class:'msg err', style:'margin-top:10px'},
-                '⚠ Less than 5% free. Remove old ISOs or grow the volume before uploading more.')
-            : (pctUsed >= 80
-                ? el('p', {class:'msg', style:'color:var(--warn);margin-top:10px'},
-                    'Volume is getting full. Consider pruning old ISOs.')
-                : null),
-        ]),
-      ]);
+      const diskCard = diskSpaceCard(disk);
 
       return el('div', {class:'grid'}, [
         diskCard,

crates/webui/src/index.html

@@ -13,7 +13,7 @@
        on the asset handlers, the practical caching window is one
        version. -->
   <link rel="stylesheet" href="/assets/app.css?v={{ASSET_VERSION}}" />
-  <link rel="icon" type="image/svg+xml" href="/assets/logo.svg?v={{ASSET_VERSION}}" />
+  <link rel="icon" type="image/svg+xml" href="/assets/logo.svg?v={{ASSET_VERSION}}&r={{LOGO_REV}}" />
   <!-- Theme is read from localStorage *before* paint to avoid the
        dark→light flash on every navigation. Falls back to the OS
        preference and finally to dark. -->
@@ -33,7 +33,7 @@
 <div class="shell">
   <aside class="sidebar">
     <div class="brand">
-      <img src="/assets/logo.svg?v={{ASSET_VERSION}}" alt="OpenPXE" />
+      <img src="/assets/logo.svg?v={{ASSET_VERSION}}&r={{LOGO_REV}}" alt="OpenPXE" />
       <strong>OpenPXE</strong>
     </div>
     <nav>

crates/webui/src/lib.rs

@@ -17,11 +17,19 @@
 ///   when we know the new one is incompatible. Combined with
 ///   `Cache-Control: no-cache, must-revalidate` on the asset handlers,
 ///   the worst-case caching window is one version.
+/// * `logo_rev` is appended to the brand-mark and favicon URLs as an
+///   extra `&r=…` token. Unlike `asset_version` it changes every time
+///   the operator swaps the custom logo, so the top-left mark updates
+///   immediately on the next page load instead of being pinned to the
+///   release version (which only changes on upgrade). `index.html`
+///   itself is served `no-cache`, so the fresh token lands as soon as
+///   the operator reloads after an upload.
 #[must_use]
-pub fn index_html(base_url: &str, asset_version: &str) -> String {
+pub fn index_html(base_url: &str, asset_version: &str, logo_rev: u64) -> String {
     INDEX_HTML
         .replace("{{BASE_URL}}", base_url)
         .replace("{{ASSET_VERSION}}", asset_version)
+        .replace("{{LOGO_REV}}", &logo_rev.to_string())
 }
 
 #[must_use]