v0.4.69: PNG boot-menu background (iPXE built from source), NFS AUTH_SYS, FleetDM logo

Three things, headlined by the long-blocked graphical PXE menu.

## 1. Graphical PXE boot background — the iVentoy feature, finally

iVentoy paints a PNG background on the PXE screen using stock iPXE
built with CONSOLE_FRAMEBUFFER + IMAGE_PNG + CONSOLE_CMD; the public
iPXE binaries omit those, so `console --picture` is a no-op on them.
We now build our own iPXE from upstream with that thin config delta
(deploy/ipxe/local/{general,console}.h).

The 8-release blocker was cc1 segfaulting when an amd64 gcc ran under
QEMU emulation on the arm64 build host. Fix: a new `ipxe-build`
Dockerfile stage pinned to $BUILDPLATFORM (native arch — no emulation)
that cross-compiles x86_64 iPXE with CROSS_COMPILE=x86_64-linux-gnu-.
The compiler runs native and emits x86_64. Validated end-to-end:
png.o + fbcon.o + pixbuf.o all compile and link (confirmed via the
linked-ELF symbol table, not just strings), ~112s, no segfault. Host
tools needed libc6-dev (dropped by --no-install-recommends; without
it the native host compile falls through to iPXE's freestanding
headers and dies on bits/stdint.h — fixed).

Server side:
- pxe_logo.rs is now a full-screen background compositor: a dark field
  (matching the WebUI theme) with the operator's uploaded logo across
  the top, or — with no upload — a default OpenPXE rainbow disc drawn
  with pure pixel math (no font/SVG deps). Always 1024x768 (iPXE
  doesn't scale; this is the universal mode). WebP/JPEG/GIF/PNG in,
  PNG out (iPXE only eats PNG).
- /branding/pxe-logo always returns a PNG now (default when no logo,
  default when SVG) so the menu always has a background.
- render_menu uses `console --picture … --top 290 || console`: paints
  the background and reserves the logo band on PNG-capable binaries
  (x86_64 UEFI), cleanly falls back to text on the others. The ASCII
  wordmark is GONE.

Only x86_64 UEFI is built from source (host-arch-agnostic cross build);
BIOS/i386/arm64 keep upstream-fetched no-PNG binaries + text fallback.
Modern clients are overwhelmingly x86_64 UEFI.

## 2. NFS AUTH_SYS credential — fixes NFS3ERR_ACCES

v0.4.68's privileged-port fix got past MNT3ERR_ACCES (mount); operators
then hit NFS3ERR_ACCES on READDIR because nfs3_client defaults to
AUTH_NONE and virtually every server exports sec=sys. We now present an
AUTH_UNIX credential (uid 0 / gid 0): no_root_squash servers treat us
as root, root_squash servers map us to anon which reads any
world-readable ISO share. Kept fixed (no UI knob) to stay dead-simple.
Hint updated: a remaining NFS3ERR_ACCES is now a server-side
permission/squash issue, not IP/auth-flavor.

## 3. FleetDM-style full-width logo (top-left)

When a custom logo is uploaded the sidebar header drops the bundled
mark + "OpenPXE" wordmark and lets the logo span the header
(left-aligned, capped 200x50, contain). Rendered server-side via a
brand-class in index_html (has_custom_logo) so there's no flash of the
default. The bundled-default case is unchanged.

Tests: 164 passing. clippy -D warnings clean. iPXE build stage
validated in isolation before the full image build.

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

crates/webui/src/app.css

@@ -117,6 +117,20 @@ code, kbd { font-family: var(--mono); font-size: 12.5px;
   letter-spacing: 0.2px;
   color: var(--fg);
 }
+
+/* v0.4.69: FleetDM-style full-width custom logo. When the operator has
+   uploaded a custom brand mark, the sidebar header drops the bundled
+   26px mark + "OpenPXE" wordmark and instead lets the uploaded image
+   span the header — left-aligned, capped at 200x50, scaled to fit
+   without distortion. The wordmark is hidden so the operator's logo is
+   the sole brand element (their logo presumably already contains their
+   name). The bundled-default case keeps the mark + wordmark. */
+.sidebar .brand.has-custom-logo { gap: 0; }
+.sidebar .brand.has-custom-logo img {
+  width: auto; height: 50px; max-width: 200px;
+  object-fit: contain; object-position: left center; flex: none;
+}
+.sidebar .brand.has-custom-logo strong { display: none; }
 .sidebar nav { padding: 10px 0; flex: 1; overflow-y: auto; }
 .sidebar nav a {
   display: flex; align-items: center; gap: 10px;

crates/webui/src/index.html

@@ -32,7 +32,7 @@
 <body>
 <div class="shell">
   <aside class="sidebar">
-    <div class="brand">
+    <div class="{{BRAND_CLASS}}">
       <img src="/assets/logo.svg?v={{ASSET_VERSION}}&r={{LOGO_REV}}" alt="OpenPXE" />
       <strong>OpenPXE</strong>
     </div>

crates/webui/src/lib.rs

@@ -24,12 +24,27 @@
 ///   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.
+/// * `has_custom_logo` switches the sidebar brand block between the
+///   bundled mark + "OpenPXE" wordmark (false) and a FleetDM-style
+///   full-width custom logo with the wordmark hidden (true). Rendered
+///   server-side so there's no flash of the default mark before JS runs.
 #[must_use]
-pub fn index_html(base_url: &str, asset_version: &str, logo_rev: u64) -> String {
+pub fn index_html(
+    base_url: &str,
+    asset_version: &str,
+    logo_rev: u64,
+    has_custom_logo: bool,
+) -> String {
+    let brand_class = if has_custom_logo {
+        "brand has-custom-logo"
+    } else {
+        "brand"
+    };
     INDEX_HTML
         .replace("{{BASE_URL}}", base_url)
         .replace("{{ASSET_VERSION}}", asset_version)
         .replace("{{LOGO_REV}}", &logo_rev.to_string())
+        .replace("{{BRAND_CLASS}}", brand_class)
 }
 
 #[must_use]