feat(catalog): implement LTD raffle system

[Diddyy]

Summary

This PR implements a comprehensive Limited Edition (LTD) system tailored for modern Habbo standards. It introduces a
weighted raffle mechanism to combat bot-sniping, a two-phase sale process (Raffle -> FCFS), and full Landing View
integration for drop countdowns.

Key Features

• Weighted Raffle Engine: Isolated LtdRaffleGrain manages a configurable buffer window (default 20s). Players join a
  pool rather than buying instantly, ensuring fair distribution during high-traffic drops.
• Fairness Criteria: Dynamic probability calculation based on multiple player metrics (configurable via
  appsettings.json):
  • Badge Count, Account Age, Achievement Score, Friend Count, Room Count, Furniture Count, and Respects.
• Two-Phase Distribution:
  • Phase 1 (Raffle): Randomized or weighted draw after the timer expires.
  • Phase 2 (FCFS): Automatic transition to "First-Come-First-Served" instant purchases once the raffle concludes.
• Smart Serial Logic:
  • Support for Habbo-style randomized serials.
  • Dynamic sequential assignment (calculated as (Total - Remaining) + 1) to ensure database consistency.
• Landing View Sync: Implemented Header 2178 (LimitedOfferAppearingNext) to display countdown timers on the Hotel
  View and automatically disable/hide "Buy" buttons until the drop is live.
• Anti-Hoarding: Optional "One-Per-Customer" toggle mapping to Habbo Error Code 6.
• Persistence: Added has_raffle_finished state tracking to ensure raffle states survive emulator restarts.

Technical Highlights

• Economic Safety: Atomic database transactions (FOR UPDATE locks) and series-specific grain isolation prevent
  double-minting or duplicate serials.
• Performance: Utilizes IPlayerGrain snapshots for weighting factor lookups to avoid database hammering during the
  20-second rush.
• Upstream Compatible: Adapted to the latest IPlayerWalletGrain refactoring (removal of GetSnapshotAsync).
• Code Quality: Clean implementation using C# 12 patterns (Primary Constructors, Collection Expressions) and
  condensed logic to avoid over-engineering.

⚙️ Configuration
Hotel owners can tune fairness and timing directly via appsettings.json:

   1 "Turbo:Catalog": {
   2   "LtdRaffle": {
   3     "DefaultBufferSeconds": 20,
   4     "RandomizeSerials": true,
   5     "LimitOnePerCustomer": true,
   6     "BadgeCount": { "Enabled": true, "BonusPerUnit": 0.02, "MaxBonus": 1.0 },
   7     "AccountAgeDays": { "Enabled": true, "BonusPerUnit": 0.0013, "MaxBonus": 0.5 }
   8   }
   9 }

🗄 Database Changes

• ltd_series: Stores drop configuration, stock levels, and raffle state.
• ltd_raffle_entries: Full audit log for every entry attempt, win, and assigned serial.

✅ Checklist

• Code formatted via csharpier.
• Builds successfully on latest origin/main.
• No duplicate serial numbers possible (Atomic Locks).
• Landing View countdown synced.