libraries: PATCH /libraries/{id} with live-apply

Adds an HTTP mutation surface for `libraries.enabled` and
`libraries.excluded_dirs`, replacing the SQL-only workflow noted in
CLAUDE.md. Apollo's Settings panel calls this from the LIBRARIES
section so the operator no longer has to ssh + sqlite3 to flip a
library off or edit its excludes.

Live-apply (no restart) via a new `live_libraries: Arc<RwLock<Vec<
Library>>>` field on AppState. The existing immutable `libraries`
Vec stays for hot-path handlers that only need stable id → root_path
lookups, avoiding a 19-call-site refactor. The watcher and
cleanup_orphaned_playlists now take the lock instead of a Vec
snapshot and re-read at the top of each tick, so `enabled` /
`excluded_dirs` changes are picked up within one
WATCH_QUICK_INTERVAL_SECONDS. The GET /libraries handler also reads
through the live view.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/main.rs

@@ -128,8 +128,12 @@ fn main() -> std::io::Result<()> {
         // Start file watcher with playlist manager and preview generator
         let playlist_mgr_for_watcher = app_state.playlist_manager.as_ref().clone();
         let preview_gen_for_watcher = app_state.preview_clip_generator.as_ref().clone();
+        // Both background jobs read from the shared `live_libraries` lock
+        // so a PATCH /libraries/{id} that flips `enabled` or edits
+        // `excluded_dirs` takes effect on the next watcher tick / cleanup
+        // tick without an ImageApi restart.
         watcher::watch_files(
-            app_state.libraries.clone(),
+            app_state.live_libraries.clone(),
             playlist_mgr_for_watcher,
             preview_gen_for_watcher,
             app_state.face_client.clone(),
@@ -142,7 +146,7 @@ fn main() -> std::io::Result<()> {
         // skips the whole cycle while any library is stale (a missing
         // source is indistinguishable from a transiently-unmounted share).
         watcher::cleanup_orphaned_playlists(
-            app_state.libraries.clone(),
+            app_state.live_libraries.clone(),
             app_state.excluded_dirs.clone(),
             app_state.library_health.clone(),
         );
@@ -280,6 +284,7 @@ fn main() -> std::io::Result<()> {
                 .service(ai::rate_insight_handler)
                 .service(ai::export_training_data_handler)
                 .service(libraries::list_libraries)
+                .service(libraries::patch_library)
                 .add_feature(add_tag_services::<_, SqliteTagDao>)
                 .add_feature(knowledge::add_knowledge_services::<_, SqliteKnowledgeDao>)
                 .add_feature(personas::add_persona_services)