refactor(electron-backend): split four files under the max-lines limit (#1278)

Split epg.events.ts (514), the embedded MPV frame-copy adapter (428) and two of its specs (547, 539) below the 400-line hard limit, and teach the baseline generator to skip files that already carry a justified file-wide eslint-disable max-lines.

The generated baseline list is unchanged: 128 entries before and after. No behavior change.

docs/architecture/sqlite-db-worker.md

@@ -386,11 +386,15 @@ Current sources:
 Main-process EPG ownership is split across focused event modules:
 
 1. `apps/electron-backend/src/app/events/epg.events.ts` registers EPG IPC
-   handlers and owns freshness/fetch orchestration.
-2. `apps/electron-backend/src/app/events/epg-worker.service.ts` owns EPG
+   handlers and delegates to the modules below.
+2. `apps/electron-backend/src/app/events/epg-fetch.service.ts` owns EPG
+   freshness checks and multi-URL fetch orchestration.
+3. `apps/electron-backend/src/app/events/epg-mapping.service.ts` owns manual
+   EPG channel-mapping resolution and CRUD at the IPC boundary.
+4. `apps/electron-backend/src/app/events/epg-worker.service.ts` owns EPG
    worker creation, renderer progress updates, fetch worker lifecycle, and
    clear-worker lifecycle.
-3. `apps/electron-backend/src/app/events/epg-query.service.ts` owns EPG
+5. `apps/electron-backend/src/app/events/epg-query.service.ts` owns EPG
    channel/program database lookups, metadata resolution, and DB row mapping.
 
 Keep worker lifecycle state out of the IPC registration layer. Add new EPG DB