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>

load-tests/web-apps.js

@@ -19,7 +19,7 @@ const apps = [
 	{ name: 'contacts', url: `${BASE}:5176` },
 	{ name: 'storage', url: `${BASE}:5178` },
 	{ name: 'presi', url: `${BASE}:5180` },
-	{ name: 'manadeck', url: `${BASE}:5181` },
+	{ name: 'cards', url: `${BASE}:5181` },
 	{ name: 'nutriphi', url: `${BASE}:5182` },
 	{ name: 'skilltree', url: `${BASE}:5183` },
 	{ name: 'photos', url: `${BASE}:5184` },