feat(casino): add Celadon Casino with slot machine, exclusive Porygon, themes, and Star Prism

[KillianHzr]

Summary

This PR adds the Celadon Casino (Game Corner) feature, complete with an industry-calibrated slot machine, exclusive Pokémon prizes, collectible app visual themes, and the ultra-rare Star Prism item:

1. Casino & Mini-Games Integration:

   • Integrated inside the Shop view using a top segmented picker: [ Shop | Casino ], keeping the popover navigation bar clean and compact.
   • Dedicated coin economy: exchange spendable tokens for casino coins across 6 tiered packages (50, 100, 500, 1,000, 5,000, 10,000 coins).

2. Calibrated Slot Machine:

   • 3-reel slot machine calibrated to real-world online casino math standards (95.8% RTP, 23.5% hit frequency):
     • Jackpot 777 (300x)
     • BAR (100x)
     • Jigglypuff (30x + Theme roll trigger)
     • Cherry (25x for 3, 7x for 2 on reels 1 & 2)
     • Pikachu (20x)
     • Poké Ball (10x)
     • Voltorb blanks (0x, authentic house edge)
   • Bet sizes: 1 coin (1 center line), 2 coins (3 horizontal lines), or 3 coins (3 horizontal + 2 diagonal lines). Multiplier selector (1x to 10x).
   • Lining up 3 Jigglypuffs triggers a weighted random lottery for unowned app themes based on rarity (Common, Uncommon, Rare, Epic, Legendary), or grants a 250-coin bonus when all themes are unlocked.

3. Prize Corner:

   • Porygon (fix: identify Codex turns by content instead of file position #137) (9,999 coins): Strictly exclusive to the Casino Prize Corner; excluded from standard egg hatching in chooseBase() and chooseBaseViaREST().
   • Other iconic prize Pokémon: Dratini (feat: split the collection tab into a species Pokédex and a catch log #147), Scyther (fix: coalesce overlapping usage refreshes and harden companion-state decoding #123), Abra (feat: 메뉴바 라이브 피드백 — 기동 dim 제거 + 2줄 적응형 폰트 #63), and Cleffa (fix: make the popover outside-click monitor idempotent (#168) #173). Purchasing a Pokémon safely archives the current companion into the Pokédex and hatches the new species with fresh egg progress.
   • Star Prism (Prisme Étoilé) (50,000 coins): Ultra-rare item used from the Bag to permanently transmute the active companion and its entire evolutionary line in the Pokédex into Shiny.

4. App Visual Themes & Settings:

   • 6 full app visual themes (Classic, Game Boy 1989, Celadon Neon, Team Rocket Dark, Indigo Plateau, Master Ball) tinting the popover window background and accent colors.
   • Theme switcher added under Settings with active preview and unlock counter.

5. State Persistence & Save Transfer:

   • casinoCoins and unlockedThemes classified under progress (preserved across machines).
   • activeTheme classified under devicePreference (kept local to each device).
   • Fully sanitized in SaveTransfer.rebasedForThisDevice and verified in unit tests.

Type of change

• Bug fix
• New feature
• Refactor / cleanup
• Documentation
• Other:

UI changes

Before	After
Shop View: Single vertical list of items and egg re-rolls with token balance header.	Shop View: Top segmented picker switching between `[ Shop
Casino: Non-existent.	Casino View: Integrated subview with coin balance, expandable coin exchange drawer, 3-reel slot machine with animated reels, payout table, and Prize Corner.
Settings View: General, Difficulty, Menu Bar, Floating Pet, Notifications, Updates, Transfer, Advanced sections.	Settings View: New "App Themes" section with active theme picker, accent color indicator, and unlocked count.
Bag View: Rare Candy, Mint, and Shiny Charm cards.	Bag View: Star Prism card with one-click transmutation action on active companion.
Popover View: System standard window background and accent tint.	Popover View: Dynamically tinted by active app visual theme.

Checklist

• swift build and swift test pass locally
• PR title and description are written in English
• UI changes are described above (before/after — images optional)
• No copyrighted assets, secrets, or private tooling references are committed (see CONTRIBUTING)
• Tests were added or updated for this change