Background-audio handoff for video + repository/player refactor

Hand video playback off to a native audio-only stream when the app is
backgrounded or locked, with no on-device video decode (UR-040). Adds
player_enter/exit_background_audio commands, an audio-only stream URL
for video items across the repository layer, and the frontend handoff
state machine wired into VideoPlayer. Includes accompanying
repository/offline/player refactoring and regenerates the traceability
matrix.

src-tauri/src/commands/playback_reporting.rs

@@ -1,5 +1,7 @@
 //! Tauri commands for playback reporting operations
 //!
+//! TRACES: UR-025, UR-019 | IR-015, JA-010, JA-011, JA-012 | DR-028
+//!
 //! These commands provide frontend access to the Rust playback reporting system,
 //! replacing the TypeScript implementation with native Rust reporting.
 //!
@@ -16,7 +18,7 @@ use crate::commands::connectivity::ConnectivityMonitorWrapper;
 use crate::commands::storage::DatabaseWrapper;
 use crate::jellyfin::client::JellyfinClient;
 use crate::jellyfin::JellyfinConfig;
-use crate::playback_reporting::{PlaybackReporter, PlaybackOperation, PlaybackContext};
+use crate::playback_reporting::{PlaybackContext, PlaybackOperation, PlaybackReporter};
 use crate::utils::conversions::seconds_to_ticks;
 
 /// Tauri state wrapper for PlaybackReporter
@@ -61,7 +63,10 @@ pub async fn playback_reporter_init(
     // Store in wrapper
     *reporter_wrapper.0.lock().await = Some(reporter);
 
-    log::info!("[PlaybackReporter] Initialized successfully for user: {}", user_id);
+    log::info!(
+        "[PlaybackReporter] Initialized successfully for user: {}",
+        user_id
+    );
     Ok(())
 }
 
@@ -205,7 +210,12 @@ mod tests {
         };
 
         // Verify enum variant can be created and pattern matched
-        if let PlaybackOperation::Start { item_id, position_ticks, context } = operation {
+        if let PlaybackOperation::Start {
+            item_id,
+            position_ticks,
+            context,
+        } = operation
+        {
             assert_eq!(item_id, "item-123");
             assert_eq!(position_ticks, 15_000_000);
             assert!(context.is_some());
@@ -225,7 +235,10 @@ mod tests {
             context: None,
         };
 
-        if let PlaybackOperation::Start { item_id, context, .. } = operation {
+        if let PlaybackOperation::Start {
+            item_id, context, ..
+        } = operation
+        {
             assert_eq!(item_id, "item-789");
             assert!(context.is_none());
         } else {
@@ -241,7 +254,12 @@ mod tests {
             is_paused: true,
         };
 
-        if let PlaybackOperation::Progress { item_id, position_ticks, is_paused } = operation {
+        if let PlaybackOperation::Progress {
+            item_id,
+            position_ticks,
+            is_paused,
+        } = operation
+        {
             assert_eq!(item_id, "item-999");
             assert_eq!(position_ticks, 30_000_000);
             assert!(is_paused);
@@ -272,7 +290,11 @@ mod tests {
             position_ticks: 120_000_000,
         };
 
-        if let PlaybackOperation::Stopped { item_id, position_ticks } = operation {
+        if let PlaybackOperation::Stopped {
+            item_id,
+            position_ticks,
+        } = operation
+        {
             assert_eq!(item_id, "item-111");
             assert_eq!(position_ticks, 120_000_000);
         } else {
@@ -364,7 +386,10 @@ mod tests {
         };
 
         let cloned = operation.clone();
-        if let PlaybackOperation::Progress { item_id, is_paused, .. } = cloned {
+        if let PlaybackOperation::Progress {
+            item_id, is_paused, ..
+        } = cloned
+        {
             assert_eq!(item_id, "item-clone");
             assert!(is_paused);
         } else {