v0.4.4: Settings tab, API reference, ISO category, branding, disk space

Settings:
- New top-level Settings tab. Carries a placeholder for the planned
  LDAP / OIDC / user-management work, the new branding controls, and
  the API reference at the bottom.
- Custom logo upload (PNG/SVG/JPEG/WebP/GIF up to 2 MB) replaces the
  bundled brand mark via /assets/logo.svg; bytes live at
  <work_dir>/branding/ and survive restart. The original "OpenPXE
  v<x.y.z>" pins to the sidebar footer for support.
- API reference rendered from a new GET /api/docs into a per-method
  coloured pill list grouped by area.

ISO category (Storage):
- New IsoCategory { Os, Tools } on IsoMeta with PUT
  /api/isos/:id/category. Storage table's Type cell becomes a
  dropdown; selecting Tools moves the ISO into the Tools submenu next
  to memtest / shell / NIC info and removes it from the OS Installers
  family submenu. Family detection still drives BIOS/UEFI / kernel
  args; only the menu placement changes.

Storage telemetry:
- New IsoStore::disk_usage (libc::statvfs, lives in iso-store so the
  http-api crate stays #![forbid(unsafe_code)]) and GET
  /api/storage/disk. The Storage tab now shows free/used/total for
  the volume hosting the ISO directory with an 80%/95% colour ramp.

UI polish:
- Brand block in the sidebar now matches the topbar height exactly,
  so the divider runs straight across the top of the app rather than
  stepping; version label moved out of the brand and pinned to the
  sidebar footer ("OpenPXE v0.4.4").
- Light-mode terminal: --terminal-bg + per-level text colours track
  the active theme rather than being hard-coded dark.
- About: lead paragraph spans the full content width; new Docs row
  links to https://openpxe.com/.

106 tests passing (was 89 in v0.4.1, +17 across branding unit tests
and new integration coverage for category / disk / docs / branding).
cargo clippy --workspace --all-targets clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

crates/http-api/tests/full_flow.rs

@@ -99,6 +99,7 @@ async fn build_state() -> (AppState, tempfile::TempDir) {
     let log_bus = LogBus::new(64);
     let hosts = HostBindings::load_or_default(dir.path());
     let boot_log = openpxe_core::BootLog::load_or_default(dir.path());
+    let branding = openpxe_core::BrandingStore::load_or_default(dir.path());
     let metrics = Metrics::new();
     let state = AppState {
         iso_store,
@@ -107,6 +108,7 @@ async fn build_state() -> (AppState, tempfile::TempDir) {
         settings,
         hosts,
         boot_log,
+        branding,
         metrics,
         smb: None,
         nfs,
@@ -1201,3 +1203,206 @@ async fn chunked_upload_rejects_offset_mismatch_without_advancing() {
     let text = String::from_utf8(body.to_vec()).unwrap();
     assert!(text.contains("expected offset 0"), "got: {text}");
 }
+
+#[tokio::test]
+async fn iso_category_switch_moves_entry_between_menus() {
+    // OS (default): appears in Linux Installers submenu and not in Tools.
+    // After flipping to Tools: gone from Linux, present under Tools.
+    let (state, _dir) = build_state().await;
+    let app = build_router(state);
+
+    let (ct, body) = multipart_iso_body("fake-alpine.iso", &fake_alpine_iso());
+    let upload = app
+        .clone()
+        .oneshot(
+            Request::builder()
+                .method("POST")
+                .uri("/api/isos")
+                .header("content-type", ct)
+                .body(Body::from(body))
+                .unwrap(),
+        )
+        .await
+        .unwrap();
+    assert_eq!(upload.status(), StatusCode::CREATED);
+
+    let (_, linux_before) = get(&app, "/boot/_linux_menu.ipxe").await;
+    let linux_before = String::from_utf8(linux_before).unwrap();
+    assert!(
+        linux_before.contains("fake-alpine-linux"),
+        "expected entry in Linux submenu (default OS):\n{linux_before}"
+    );
+    let (_, tools_before) = get(&app, "/boot/_tools_menu.ipxe").await;
+    let tools_before = String::from_utf8(tools_before).unwrap();
+    assert!(
+        !tools_before.contains("fake-alpine-linux"),
+        "OS-category ISO shouldn't appear in Tools yet:\n{tools_before}"
+    );
+
+    // Flip to Tools.
+    let (s, _) = put_json(
+        &app,
+        "/api/isos/fake-alpine/category",
+        r#"{"category":"tools"}"#,
+    )
+    .await;
+    assert_eq!(s, StatusCode::OK);
+
+    let (_, linux_after) = get(&app, "/boot/_linux_menu.ipxe").await;
+    let linux_after = String::from_utf8(linux_after).unwrap();
+    assert!(
+        !linux_after.contains("fake-alpine-linux"),
+        "Tools-category ISO should NOT appear in Linux submenu:\n{linux_after}"
+    );
+    let (_, tools_after) = get(&app, "/boot/_tools_menu.ipxe").await;
+    let tools_after = String::from_utf8(tools_after).unwrap();
+    assert!(
+        tools_after.contains("fake-alpine-linux"),
+        "Tools-category ISO should appear in Tools submenu:\n{tools_after}"
+    );
+}
+
+#[tokio::test]
+async fn iso_category_unknown_value_returns_400() {
+    let (state, _dir) = build_state().await;
+    let app = build_router(state);
+    let (ct, body) = multipart_iso_body("fake-alpine.iso", &fake_alpine_iso());
+    app.clone()
+        .oneshot(
+            Request::builder()
+                .method("POST")
+                .uri("/api/isos")
+                .header("content-type", ct)
+                .body(Body::from(body))
+                .unwrap(),
+        )
+        .await
+        .unwrap();
+
+    let (s, body) = put_json(
+        &app,
+        "/api/isos/fake-alpine/category",
+        r#"{"category":"gibberish"}"#,
+    )
+    .await;
+    assert_eq!(s, StatusCode::BAD_REQUEST);
+    let text = std::str::from_utf8(&body).unwrap();
+    assert!(text.contains("unknown category"), "got: {text}");
+}
+
+#[tokio::test]
+async fn iso_category_unknown_id_returns_404() {
+    let (state, _dir) = build_state().await;
+    let app = build_router(state);
+    let (s, _) = put_json(
+        &app,
+        "/api/isos/does-not-exist/category",
+        r#"{"category":"tools"}"#,
+    )
+    .await;
+    assert_eq!(s, StatusCode::NOT_FOUND);
+}
+
+#[tokio::test]
+async fn storage_disk_endpoint_reports_volume_stats() {
+    let (state, _dir) = build_state().await;
+    let app = build_router(state);
+    let (s, body) = get(&app, "/api/storage/disk").await;
+    assert_eq!(s, StatusCode::OK);
+    let v: serde_json::Value = serde_json::from_slice(&body).unwrap();
+    // statvfs always returns something on the tempdir filesystem; check
+    // that the shape is sane (total >= used >= 0 and total >= available).
+    assert!(v["total_bytes"].as_u64().unwrap() > 0, "got {v}");
+    let total = v["total_bytes"].as_u64().unwrap();
+    let avail = v["available_bytes"].as_u64().unwrap();
+    let used = v["used_bytes"].as_u64().unwrap();
+    assert!(total >= avail, "{v}");
+    assert!(total >= used,  "{v}");
+    assert!(v["path"].as_str().unwrap().contains("isos"), "got {v}");
+}
+
+#[tokio::test]
+async fn api_docs_lists_known_endpoints() {
+    let (state, _dir) = build_state().await;
+    let app = build_router(state);
+    let (s, body) = get(&app, "/api/docs").await;
+    assert_eq!(s, StatusCode::OK);
+    let v: serde_json::Value = serde_json::from_slice(&body).unwrap();
+    let groups = v["groups"].as_array().expect("groups array");
+    assert!(!groups.is_empty());
+    // Flatten the paths and confirm a handful of the routes that real
+    // operators will look up are documented.
+    let mut paths: Vec<String> = Vec::new();
+    for g in groups {
+        for ep in g["endpoints"].as_array().unwrap() {
+            paths.push(ep["path"].as_str().unwrap().into());
+        }
+    }
+    for needle in [
+        "/api/isos",
+        "/api/isos/:id/category",
+        "/api/storage/disk",
+        "/api/branding/logo",
+        "/api/boot-log",
+        "/metrics",
+    ] {
+        assert!(
+            paths.iter().any(|p| p == needle),
+            "expected {needle} in docs; got {paths:?}"
+        );
+    }
+}
+
+#[tokio::test]
+async fn branding_clear_when_no_logo_is_no_content() {
+    // No-op clear should still 204 — it's not an error to revert to
+    // the default when there's nothing to revert from.
+    let (state, _dir) = build_state().await;
+    let app = build_router(state);
+    let res = app
+        .oneshot(
+            Request::builder()
+                .method("DELETE")
+                .uri("/api/branding/logo")
+                .body(Body::empty())
+                .unwrap(),
+        )
+        .await
+        .unwrap();
+    assert_eq!(res.status(), StatusCode::NO_CONTENT);
+}
+
+#[tokio::test]
+async fn status_exposes_custom_logo_flag() {
+    let (state, _dir) = build_state().await;
+    let app = build_router(state);
+    let (s, body) = get(&app, "/api/status").await;
+    assert_eq!(s, StatusCode::OK);
+    let v: serde_json::Value = serde_json::from_slice(&body).unwrap();
+    assert_eq!(
+        v["custom_logo"].as_bool(),
+        Some(false),
+        "fresh state has no custom logo: {v}"
+    );
+}
+
+async fn put_json(router: &axum::Router, path: &str, body: &str) -> (StatusCode, Vec<u8>) {
+    let res = router
+        .clone()
+        .oneshot(
+            Request::builder()
+                .method("PUT")
+                .uri(path)
+                .header("content-type", "application/json")
+                .body(Body::from(body.to_owned()))
+                .unwrap(),
+        )
+        .await
+        .unwrap();
+    let status = res.status();
+    let bytes = axum::body::to_bytes(res.into_body(), usize::MAX)
+        .await
+        .unwrap()
+        .to_vec();
+    (status, bytes)
+}