feat(offline): play downloaded video, and drain the offline sync queue (0.4.6)

Bundles this session's work plus the concurrent search/offline/player changes.
Every gate passes on the combined tree: 885 frontend tests, 610 Rust tests,
clippy clean, boundary clean, trace coverage 86%.

Offline video playback — four separate defects, each of which alone stopped it:

  DR-133  A completed download's file_path is already absolute (the worker
          rewrites it on completion), but the player rooted it a second time and
          handed the webview /data/user/0/app//data/user/0/app/videos/x.mp4.
  DR-134  The asset protocol was never enabled: no protocol-asset feature and no
          assetProtocol config, so convertFileSrc produced URLs nothing answered.
          Also silently defeated the cached-thumbnail path, which fails soft to
          the server copy and hid it whenever the server was reachable.
  DR-137  Tauri's asset protocol answers a range-less request by reading the
          whole file into memory, and only advertises Accept-Ranges from inside
          its range branch, so the first request never learns ranges exist.
          Chromium gave up with PIPELINE_ERROR_READ after ~31s. Local media is
          now served by a loopback HTTP server: bounded 4 MiB chunks streamed
          from the file handle, every response length-delimited, and a range-less
          request answered with one chunk rather than the file. Confined by a
          per-session token and to the app data directory, because loopback is
          shared between apps on Android.
  DR-138  Release builds set usesCleartextTraffic=false, so Android rejected the
          request to that server before any I/O. A network-security-config
          exempts 127.0.0.1 only; a remote server must still be HTTPS.

Downloads:

  DR-135  download_item never records media_type and the reconnect resolver read
          that NULL as 'audio', so a movie queued from a media card had its URL
          resolved by get_audio_stream_url and completed as an audio-only
          transcode. The item's own type now decides.
  DR-136  Rows already downloaded that way are requeued on reconnect, since
          prevention alone leaves them reading "downloaded" and still unplayable.

Known limitation: a download taken at `original` quality is a byte copy of the
source, so it can be any container. One such file is an AVI holding XVID, which
the webview cannot play in any case — the media server serves it correctly and
Chromium refuses it. That needs either a transcoded download preset or the
native ExoPlayer surface work, and is not addressed here.

Also fixes two ID collisions between concurrent work: DR-143 defined twice
(search vs offline gate) and UT-131 defined twice (Episode Focus hero vs channel
cap). The search requirement is now DR-147 and the channel-cap test UT-141, with
their code references and matrix rows updated.

src/routes/settings/+page.svelte

@@ -1,4 +1,4 @@
-<!-- TRACES: UR-023, UR-027, UR-029, UR-057 | DR-030, DR-048, DR-077, DR-086 -->
+<!-- TRACES: UR-023, UR-025, UR-027, UR-029, UR-057 | DR-030, DR-048, DR-077, DR-086, DR-132 -->
 <script lang="ts">
   import { onMount } from "svelte";
   import { commands } from "$lib/api/bindings";
@@ -20,6 +20,7 @@
   } from "$lib/services/imageCache";
   import { getCacheConfig, updateCacheConfig } from "$lib/services/preload";
   import SearchGroupOrderList from "$lib/components/settings/SearchGroupOrderList.svelte";
+  import PendingSyncList from "$lib/components/sync/PendingSyncList.svelte";
   import { library, viewMode } from "$lib/stores/library";
   import {
     isNetworkDetectionSupported,
@@ -674,6 +675,18 @@
         </div>
       </div>
 
+      <!-- Pending server updates. Lives here as well as behind the offline
+           banner's badge, because a row that keeps failing is still queued once
+           the server is reachable again — when no banner is on screen.
+           TRACES: UR-025 | DR-132 -->
+      <div class="border-t border-gray-700 pt-6">
+        <h2 class="text-2xl font-bold text-white mb-4">Waiting to sync</h2>
+
+        <div class="bg-[var(--color-surface)] rounded-lg p-6">
+          <PendingSyncList />
+        </div>
+      </div>
+
       <!-- Image Cache Settings -->
       <div class="border-t border-gray-700 pt-6">
         <h2 class="text-2xl font-bold text-white mb-4">Image Cache</h2>