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-tauri/src/repository/device_profile.rs

@@ -26,7 +26,7 @@ const MAX_SUPPORTED_AUDIO_CHANNELS: u32 = 8;
 /// A missing or zero reading means "route not established yet", not "no audio":
 /// fall back to stereo rather than claiming a capability we have not seen.
 ///
-/// TRACES: UR-004 | DR-141 | UT-131
+/// TRACES: UR-004 | DR-141 | UT-141
 pub fn clamp_max_audio_channels(reported: Option<u32>) -> u32 {
     match reported {
         Some(channels) if channels >= 1 => channels.min(MAX_SUPPORTED_AUDIO_CHANNELS),
@@ -37,7 +37,7 @@ pub fn clamp_max_audio_channels(reported: Option<u32>) -> u32 {
 /// The channel cap for this device, reading the platform's report where one
 /// exists.
 ///
-/// TRACES: UR-004 | DR-141 | UT-131
+/// TRACES: UR-004 | DR-141 | UT-141
 pub fn max_audio_channels() -> u32 {
     #[cfg(target_os = "android")]
     let reported = crate::player::get_detected_codecs().and_then(|(_, _, channels)| channels);

src-tauri/src/repository/hybrid.rs

@@ -812,6 +812,11 @@ impl MediaRepository for HybridRepository {
         self.online.clear_watch_history(item_id).await
     }
 
+    async fn mark_played(&self, item_id: &str) -> Result<(), RepoError> {
+        // Write operations go directly to server
+        self.online.mark_played(item_id).await
+    }
+
     async fn get_person(&self, person_id: &str) -> Result<MediaItem, RepoError> {
         let offline = Arc::clone(&self.offline);
         let online = Arc::clone(&self.online);
@@ -1237,6 +1242,10 @@ mod tests {
             unimplemented!()
         }
 
+        async fn mark_played(&self, _item_id: &str) -> Result<(), RepoError> {
+            unimplemented!()
+        }
+
         async fn get_person(&self, _person_id: &str) -> Result<MediaItem, RepoError> {
             unimplemented!()
         }
@@ -1507,6 +1516,10 @@ mod tests {
             unimplemented!()
         }
 
+        async fn mark_played(&self, _item_id: &str) -> Result<(), RepoError> {
+            unimplemented!()
+        }
+
         async fn get_person(&self, _person_id: &str) -> Result<MediaItem, RepoError> {
             unimplemented!()
         }

src-tauri/src/repository/mod.rs

@@ -235,6 +235,14 @@ pub trait MediaRepository: Send + Sync {
     /// TRACES: UR-064 | DR-106
     async fn clear_watch_history(&self, item_id: &str) -> Result<(), RepoError>;
 
+    /// Mark an item played — the inverse of `clear_watch_history`. Needed by the
+    /// sync-queue drain, which replays `mark_played` rows queued while the
+    /// server was unreachable; reporting a stop at a made-up position was the
+    /// previous stand-in and does not set the played flag reliably.
+    ///
+    /// TRACES: UR-025 | DR-131 | JA-035
+    async fn mark_played(&self, item_id: &str) -> Result<(), RepoError>;
+
     /// Get person details
     async fn get_person(&self, person_id: &str) -> Result<MediaItem, RepoError>;
 

src-tauri/src/repository/offline.rs

@@ -2050,6 +2050,12 @@ impl MediaRepository for OfflineRepository {
         Err(RepoError::Offline)
     }
 
+    async fn mark_played(&self, _item_id: &str) -> Result<(), RepoError> {
+        // Offline the local flag is written by `storage_mark_played` and the
+        // server half is queued in `sync_queue`; this path has no server.
+        Err(RepoError::Offline)
+    }
+
     async fn get_person(&self, person_id: &str) -> Result<MediaItem, RepoError> {
         let query = Query::with_params(
             "SELECT id, name, overview, primary_image_tag

src-tauri/src/repository/online.rs

@@ -1893,6 +1893,48 @@ impl MediaRepository for OnlineRepository {
         result
     }
 
+    /// `POST /Users/{userId}/PlayedItems/{itemId}` — the mirror image of
+    /// `clear_watch_history`.
+    ///
+    /// TRACES: UR-025 | DR-131 | JA-035
+    async fn mark_played(&self, item_id: &str) -> Result<(), RepoError> {
+        let endpoint = format!("/Users/{}/PlayedItems/{}", self.user_id, item_id);
+        let url = format!("{}{}", self.server_url, endpoint);
+
+        let result = async {
+            let request = self
+                .http_client
+                .client
+                .post(&url)
+                .header("X-Emby-Authorization", self.auth_header())
+                .header("Content-Length", "0")
+                .build()
+                .map_err(|e| RepoError::Network {
+                    message: format!("Failed to build request: {}", e),
+                })?;
+
+            let response = self
+                .http_client
+                .request_with_retry(request)
+                .await
+                .map_err(|e| RepoError::Network {
+                    message: e.to_string(),
+                })?;
+
+            if !response.status().is_success() {
+                return Err(RepoError::Server {
+                    message: format!("HTTP {}", response.status()),
+                });
+            }
+
+            Ok(())
+        }
+        .await;
+
+        self.report_outcome(&result).await;
+        result
+    }
+
     async fn get_person(&self, person_id: &str) -> Result<MediaItem, RepoError> {
         let endpoint = format!("/Users/{}/Items/{}", self.user_id, person_id);
         let item: JellyfinItem = self.get_json(&endpoint).await?;