v0.2.0 — pre-beta: per-MAC bindings, /metrics, themes, animated forge

This is the bulk pre-beta cleanup pass. Bumps the workspace to 0.2.0.
Test count is 56 -> 66 (+10), clippy is fully clean across the
workspace (was several dozen warnings).

## New features

**Per-MAC host bindings** (Tinkerbell smee pattern). New
`HostBindings` registry maps a MAC -> preferred boot target, persisted
to <work_dir>/hosts.json. The DHCP reply now embeds `?mac=${mac}` in
the boot.ipxe URL; iPXE substitutes the literal MAC client-side, so
the HTTP layer can short-circuit straight to the bound target instead
of rendering the menu. Reserved menu shortcuts (`_local`, `_gate`,
`_tools_menu`) are valid targets too. New /api/hosts CRUD + a Hosts
tab in the sidebar.

**Prometheus `/metrics`** endpoint. Tiny lock-free implementation —
just AtomicU64s and a Display impl, no `prometheus` / `metrics-rs`
dep. Counters: DHCP replies (per arch label), DHCP declined, TFTP
transfers (per status), TFTP bytes, HTTP requests (per route).
Gauges: ISO count, client count, gate count, gate-imaging, NFS active
mounts, uptime, build info. Plain text exposition format,
text/plain;version=0.0.4 content-type, no auth (all metric values are
non-sensitive counts).

**Light + dark themes**. CSS tokens on `:root` and
`:root[data-theme=light]`, swap by toggle button (top-right) or `T`
hotkey. Persisted in localStorage; pre-paint inline script avoids
dark<->light flash. Light palette designed against the Netbox Labs
reference screenshot — near-white surfaces, soft grey dividers,
accent unchanged for brand consistency. Terminal pane stays dark in
both themes (it's a console, that's the right read).

**Animated SVG logo + forge widget**. New `logo.svg` is a refined
silver/grey anvil. New `anvil-forge.svg` adds rising sparks and a
pulsing underglow via SMIL — pure SVG, no GIF, no JS animation loop.
Used:
  - in the **forge progress** widget on Dashboard + Forge Gate, paired
    with a `linear-gradient(warn -> accent)` bar with a moving sheen;
    goes idle (greyscale, no sheen) at zero imaging load
  - in the page-load `<div class=loader>` that replaces the old
    "Loading..." text

## Code cleanup pass

`cargo clippy --workspace --all-targets` is now warning-free. Spot
fixes across the tree:
  - `format!()`-into-`String` -> `std::fmt::Write::write!`
  - manual reverse comparators -> `Reverse`
  - `map_or(false, ...)` -> `is_some_and`
  - redundant closures -> method references
  - `r#"..."#` raw strings without `"` -> `r"..."`
  - `std::io::Error::new(Other, ...)` -> `Error::other`
  - `as i32` on `c.id()` -> `cast_signed()`
  - merged identical match arms

## Windows workflow validation

New integration test synthesizes an ISO9660 with the SOURCES\\BOOT.WIM
sentinel, uploads it, asserts:
  1. introspection labels it `windows_pe` with has_boot_wim=true,
  2. the boot entry is `BootKind::Wimboot` with all five canonical
     files (bootmgr, bootmgr.efi, bcd, boot.sdi, boot.wim),
  3. the rendered iPXE script chains wimboot with `initrd --name`
     entries for each file, and
  4. NO trust-store strings appear in the rendered output: bcdedit,
     testsigning, certutil, httpdisk, and test-signed are all
     explicitly forbidden as a hard guarantee.

WinPE bootstrap (startnet.cmd) picks up the Bootimus v0.1.58 lessons:
explicit `net start Workstation` before `net use` to avoid the SMB
client lazy-init race, and surfaces errors instead of blind retries.

## Docs

architecture.md gains a "Phase 5" section explaining the host-bindings
+ metrics + theming + Windows-test work, plus a refreshed "deferred
to Phase 6" list (real-hardware integration, autounattend library,
distro profile manifest, WoL trigger, syslog receiver, IPv6).
README updates the status line, the "what it does" list, and adds
the new Hosts/Terminal tab names.

crates/iso-store/src/store.rs

@@ -19,9 +19,10 @@ use tokio::io::AsyncWriteExt;
 /// `Nfs` entries point at a file inside a remote share that the
 /// `NfsManager` is keeping mounted. We resolve the on-disk path lazily
 /// in [`IsoStore::iso_path_for`] using the `nfs_root` set at startup.
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
 #[serde(tag = "kind", rename_all = "snake_case")]
 pub enum IsoSource {
+    #[default]
     Local,
     Nfs {
         mount_id: String,
@@ -30,12 +31,6 @@ pub enum IsoSource {
     },
 }
 
-impl Default for IsoSource {
-    fn default() -> Self {
-        Self::Local
-    }
-}
-
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct IsoMeta {
     /// Stable slug used in URLs (derived from the uploaded filename).
@@ -156,7 +151,11 @@ impl IsoStore {
         while let Some(e) = entries.next_entry().await? {
             let p = e.path();
             if p.extension().and_then(|s| s.to_str()) != Some("json") { continue; }
-            if !p.file_name().and_then(|s| s.to_str()).map_or(false, |n| n.ends_with(".meta.json")) {
+            if !p
+                .file_name()
+                .and_then(|s| s.to_str())
+                .is_some_and(|n| n.ends_with(".meta.json"))
+            {
                 continue;
             }
             if let Ok(text) = tokio::fs::read_to_string(&p).await {
@@ -218,7 +217,8 @@ impl IsoStore {
     pub fn list(&self) -> Vec<IsoMeta> {
         let g = self.inner.read();
         let mut v: Vec<_> = g.isos.values().cloned().collect();
-        v.sort_by(|a, b| b.uploaded_at.cmp(&a.uploaded_at));
+        // Newest-first by upload time.
+        v.sort_by_key(|m| std::cmp::Reverse(m.uploaded_at));
         v
     }
 
@@ -403,9 +403,9 @@ fn linux_cmdline(family: DistroFamily, id: &str) -> String {
         DistroFamily::OpenSuse => format!(
             "install={iso_url} netsetup=dhcp"
         ),
-        DistroFamily::Arch => format!(
-            "archiso_http_srv=${{base-url}}/iso/ archisobasedir=arch ip=dhcp copytoram"
-        ),
+        DistroFamily::Arch => {
+            "archiso_http_srv=${base-url}/iso/ archisobasedir=arch ip=dhcp copytoram".to_string()
+        }
         DistroFamily::Alpine => format!(
             "alpine_repo=${{base-url}}/iso/{id}/ modloop=${{base-url}}/iso/{id}/boot/modloop-lts ip=dhcp"
         ),