refactor: rename ManaDeck to Cards across entire monorepo

Rename the flashcard/deck management app from ManaDeck to Cards:
- Directory: apps/manadeck → apps/cards, packages/manadeck-database → packages/cards-database
- Packages: @manadeck/* → @cards/*, @manacore/manadeck-database → @manacore/cards-database
- Domain: manadeck.mana.how → cards.mana.how
- Storage: manadeck-storage → cards-storage
- Database: manadeck → cards
- All shared packages, infra configs, services, i18n, and docs updated
- 244 files changed, zero remaining manadeck references

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/matrix/apps/web/src/lib/data/bots.ts

@@ -372,9 +372,9 @@ export const BOTS: BotInfo[] = [
 		],
 	},
 	{
-		id: 'manadeck-bot',
-		name: 'ManaDeck Bot',
-		matrixUserId: '@manadeck-bot:matrix.mana.how',
+		id: 'cards-bot',
+		name: 'Cards Bot',
+		matrixUserId: '@cards-bot:matrix.mana.how',
 		description: 'Lernkarten und Spaced Repetition',
 		longDescription:
 			'Erstelle und lerne mit Karteikarten. Nutzt Spaced Repetition für optimales Lernen.',