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>

.claude/guidelines/hono-server.md

@@ -87,7 +87,7 @@ Only servers that need their own database use Drizzle. Most apps rely on mana-sy
 
 **Servers with Drizzle:** chat, todo, moodlit, context, planta, presi, traces, uload, wisekeep, news
 
-**Servers without Drizzle (mana-sync only):** calendar, contacts, manadeck, mukke, nutriphi, picture, questions, storage
+**Servers without Drizzle (mana-sync only):** calendar, contacts, cards, mukke, nutriphi, picture, questions, storage
 
 ## Running Servers
 

.claude/guidelines/sveltekit-web.md

@@ -811,7 +811,7 @@ All web apps with backends now use the runtime injection pattern:
 
 ### Apps That May Need Fixing
 
-- ❓ `manadeck/apps/web` - Check if using dynamic URLs
+- ❓ `cards/apps/web` - Check if using dynamic URLs
 - ❓ `manacore/apps/web` - Check if using dynamic URLs
 
 ### Quick Checklist for New SvelteKit Apps