feat: enhance EPG service with channel metadata fetching and update M3U module documentation

Entire-Checkpoint: c6e522b4276c

docs/architecture/m3u-playlist-module.md

@@ -213,10 +213,28 @@ For performance optimization, channels are pre-enriched with EPG data:
 ```typescript
 interface EnrichedChannel extends Channel {
     epgProgram: EpgProgram | null | undefined;
+    logo: string;                // Playlist tvg-logo first, XMLTV icon fallback second
     progressPercentage: number;  // Pre-computed by parent
 }
 ```
 
+The renderer now keeps two lookup maps for M3U collection views:
+
+- `channelEpgMap` for current-program preview data
+- `channelIconMap` for XMLTV channel icon fallback data
+
+Logo resolution is runtime-only and follows this rule:
+
+1. playlist `tvg-logo`
+2. matched XMLTV `<channel><icon src="...">`
+3. generic `live_tv` fallback in the list item component
+
+EPG lookup keys use the same precedence in both program and icon paths:
+
+1. `tvg-id`
+2. `tvg-name`
+3. channel name
+
 ### Performance Optimizations
 
 | Optimization | Implementation |
@@ -232,7 +250,7 @@ interface EnrichedChannel extends Channel {
 ### Tab Components
 
 #### AllChannelsTabComponent
-- **Inputs**: `channels`, `channelEpgMap`, `progressTick`, `shouldShowEpg`, `itemSize`, `activeChannelUrl`, `favoriteIds`
+- **Inputs**: `channels`, `channelEpgMap`, `channelIconMap`, `progressTick`, `shouldShowEpg`, `itemSize`, `activeChannelUrl`, `favoriteIds`
 - **Outputs**: `channelSelected`, `favoriteToggled`
 - **Features**: Search with 300ms debounce, virtual scrolling, no-results placeholder
 
@@ -242,7 +260,7 @@ interface EnrichedChannel extends Channel {
 - **Features**: Expansion panels, infinite scroll with IntersectionObserver, lazy loading
 
 #### FavoritesTabComponent
-- **Inputs**: `favorites`, `channelEpgMap`, `progressTick`, `shouldShowEpg`, `activeChannelUrl`
+- **Inputs**: `favorites`, `channelEpgMap`, `channelIconMap`, `progressTick`, `shouldShowEpg`, `activeChannelUrl`
 - **Outputs**: `channelSelected`, `favoriteToggled`, `favoritesReordered`
 - **Features**: Drag-and-drop reordering with CDK DragDrop
 
@@ -261,6 +279,9 @@ class EpgService {
     // Batch fetch current programs
     getCurrentProgramsForChannels(channelIds: string[]): Observable<Map<string, EpgProgram>>;
 
+    // Batch fetch XMLTV channel metadata for logo fallback
+    getChannelMetadataForChannels(channelIds: string[]): Observable<Map<string, EpgChannelMetadata | null>>;
+
     // Observables
     epgAvailable$: Observable<boolean>;
     currentEpgPrograms$: Observable<EpgProgram[]>;

libs/epg/data-access/src/lib/epg.service.ts

@@ -3,7 +3,7 @@ import { MatSnackBar } from '@angular/material/snack-bar';
 import { TranslateService } from '@ngx-translate/core';
 import { BehaviorSubject, forkJoin, from, Observable, of } from 'rxjs';
 import { catchError, map, tap, timeout } from 'rxjs/operators';
-import { EpgProgram } from 'shared-interfaces';
+import { EpgChannelMetadata, EpgProgram } from 'shared-interfaces';
 import { normalizeEpgPrograms } from './epg-program-normalization.util';
 
 interface CachedProgram {
@@ -11,6 +11,12 @@ interface CachedProgram {
     timestamp: number;
 }
 
+type EpgChannelMetadataApi = {
+    getEpgChannelMetadata?: (
+        channelIds: string[]
+    ) => Promise<Record<string, EpgChannelMetadata | null>>;
+};
+
 @Injectable({
     providedIn: 'root',
 })
@@ -219,6 +225,49 @@ export class EpgService {
         );
     }
 
+    getChannelMetadataForChannels(
+        channelIds: string[]
+    ): Observable<Map<string, EpgChannelMetadata | null>> {
+        if (!this.isDesktop) {
+            return of(new Map());
+        }
+
+        const normalizedChannelIds = Array.from(
+            new Set(
+                channelIds
+                    .map((channelId) => channelId.trim())
+                    .filter((channelId) => channelId.length > 0)
+            )
+        );
+
+        if (normalizedChannelIds.length === 0) {
+            return of(new Map());
+        }
+
+        const getEpgChannelMetadata = (
+            window.electron as EpgChannelMetadataApi | undefined
+        )?.getEpgChannelMetadata;
+
+        if (typeof getEpgChannelMetadata !== 'function') {
+            return of(new Map());
+        }
+
+        return from(getEpgChannelMetadata(normalizedChannelIds)).pipe(
+            map((metadataByChannelId) => {
+                return new Map<string, EpgChannelMetadata | null>(
+                    normalizedChannelIds.map((channelId) => [
+                        channelId,
+                        metadataByChannelId[channelId] ?? null,
+                    ])
+                );
+            }),
+            catchError((err) => {
+                console.error('EPG get channel metadata error:', err);
+                return of(new Map<string, EpgChannelMetadata | null>());
+            })
+        );
+    }
+
     /**
      * Clears the program cache (useful when EPG is refreshed)
      */

libs/m3u-state/src/index.ts

@@ -1,4 +1,5 @@
 export * from './lib/actions';
+export * from './lib/channel-epg-lookup.util';
 export * from './lib/effects';
 export * from './lib/external-player-payload.util';
 export * from './lib/reducers';