Feature/cards decks foundation

[KellyBallinger05]

Summary

Bundles the initial Cards + Decks foundation work:

• Card detail + edit flow in Studio
• Deck creation + deck list page
• Minimal deck builder (add/remove cards)
• Deck-size rules stored on the Game record + basic deck size feedback

What’s Included

Cards

• /studio/cards/[id] card detail page
• /studio/cards/[id]/edit card edit page + server action validation + redirect

Decks

• /studio/decks decks index page (list decks)
• /studio/decks/new create deck page + server action
• /studio/decks/[id] minimal deck builder (add/remove cards via deck_cards)

Rules / DB

• games.min_deck_size + games.max_deck_size (backend source of truth)
• RLS policies for decks and deck_cards (ownership enforced via parent game/deck)

How to Test

1. Cards:
   • Navigate to /studio/cards/<id> and /studio/cards/<id>/edit
   • Edit fields and confirm save redirects back with ?updated=1
2. Deck creation:
   • Go to /studio/decks/new
   • Select a game, create deck, confirm redirect shows success
3. Builder:
   • From /studio/decks, open a deck builder
   • Add/remove cards and confirm deck_cards updates + builder view updates

Known Issue

• Deck count on /studio/decks can appear stale after navigating back from the builder due to client-side caching/prefetch. Data is correct in DB and builder view; UI refresh behavior will be addressed in a follow-up PR. Still trying to figure this out.

[KellyBallinger05]

Resolved the merge conflict in studio/decks/page.tsx again, same situation as the other PR. Kept the decks list with card counts and size validation. The DeckBuilderClient component is still in components/DeckBuilderClient.tsx, just not being used / wired up together yet.