fix(library-db): name slow-write ops for macOS stall diagnosis (#1043)

* fix(library-db): name slow-write ops for macOS stall diagnosis (#1040)

Replace generic op=misc labels on production library-db write paths with
stable module.action names (sync_state.*, track.*, tombstone.*, cmd.*, …)
so SLOW write logs pinpoint the call site. Document the naming convention
on LibraryStore::with_conn.

Diagnostic step for #1040 — no behaviour change.

* docs: add CHANGELOG and credits for PR #1043

Library-db slow-write op naming diagnostic for issue #1040.

src-tauri/crates/psysonic-library/src/store.rs

@@ -103,6 +103,11 @@ impl LibraryStore {
     }
 
     /// Writer connection — sync ingest, migrations, mutations.
+    ///
+    /// `op` is logged on slow writes (`[library-db] SLOW write op=…`) — use a
+    /// stable `module.action` label (e.g. `sync_state.set_sync_phase`,
+    /// `track.upsert_batch_remap`), not the generic `"misc"`, so production
+    /// stalls can be attributed to a specific call site.
     pub(crate) fn with_conn<R>(
         &self,
         op: &'static str,