feat: manual EPG-to-channel mapping with mapping fallback (#1165)

* feat(epg): manual EPG-to-channel mapping with mapping fallback in all EPG paths

* fix: epg mapping in live tv list

* fix(epg): harden manual EPG mapping — upgrade safety, perf, playlist-scoped keys

Follow-up fixes on top of the manual EPG-to-channel mapping feature:

- epg-database: dedupe existing epg_programs rows before creating the
  unique (channel_id, start, title) index — a plain CREATE UNIQUE INDEX
  crashed the EPG worker on upgrade when historical duplicates exist;
  replace INSERT OR REPLACE with ON CONFLICT DO UPDATE so the
  epg_programs_fts delete trigger is not bypassed (REPLACE skips delete
  triggers unless recursive_triggers is on), with a plain-INSERT
  fallback when the index cannot be created
- db: add idx_content_epg_channel — the mapping fallback scanned the
  whole content table on every single-channel EPG lookup
- keys: scope Xtream mapping keys per playlist via shared
  buildXtreamEpgMappingKey (xtream:{playlistId}:{id}) — bare stream ids
  collide across portals; the backend fallback now joins categories to
  resolve the playlist id
- pwa: hide "Map EPG channel" entries behind the supportsEpgMapping
  capability — the menu item was a dead end in the PWA
- parser: parse the XMLTV offset sign from the string — Math.sign(0)
  dropped the minutes of ±00:xx offsets
- cleanup: typed window.electron access instead of ad-hoc casts, drop
  unused resolveChannelId and dialog data field, shared
  EpgMappingDialogComponent.open() for all seven call sites
- dialog UX: minimum-characters search hint, save/remove snackbars,
  current mapping shows the EPG channel display name,
  takeUntilDestroyed on the search stream
- i18n: fill the new keys in all 17 locales
- tests: cover mapping CRUD/search escaping, the dedup-index guard,
  offset parsing and playlist-scoped keys; update stale stream-resolver
  specs for the new 50-item limit and 10s timeout

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(epg): escape backslashes in EPG channel search LIKE pattern

CodeQL js/incomplete-sanitization: a lone trailing backslash in the
search term paired with the closing wildcard under the ESCAPE clause
and corrupted the pattern.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* perf(epg): batch mapping lookups in the viewport preview queue

Expose the existing getEpgMappingsBatch operation over a new
EPG_MAPPING_GET_BATCH IPC channel and use it in resolveManualMappings —
the per-entry lookup issued one IPC round-trip per visible channel on
every scroll event.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* perf(epg): batch mapping prefetch in the collection preview loader

Resolve all candidate mapping keys for an Xtream preview batch with a
single getEpgMappingsBatch IPC call instead of per-channel lookups.
Also fix a worker early-exit: a channel without tvgId/name returned out
of the shared-iterator loop and silently killed one of the three
concurrent preview workers.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: 4gray <serega05@gmail.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

libs/services/src/lib/runtime-capabilities.service.ts

@@ -115,6 +115,15 @@ export class RuntimeCapabilitiesService {
         return this.hasElectronMethod('searchEpgPrograms');
     }
 
+    get supportsEpgMapping(): boolean {
+        return (
+            this.hasElectronMethod('getEpgMapping') &&
+            this.hasElectronMethod('setEpgMapping') &&
+            this.hasElectronMethod('deleteEpgMapping') &&
+            this.hasElectronMethod('searchEpgChannels')
+        );
+    }
+
     get supportsSqlite(): boolean {
         return [
             'dbDeleteAllPlaylists',