feat: implement community events, inventory, battle pass, and account management (#451, #452, #453, #454) - #456

What does this PR do?

Implements Community Events with scheduling, milestones, leaderboards, and rewards (#451); Player Inventory and item management with category limits and item sorting/filtering (#452); Seasonal Battle Pass with progression tiers, dual free/premium tracks, and retroactive reward claims (#453); and Account Progression Reset with backup snapshots, token confirmation safety delay, account linking, and audit logging (#454).

Why?

closes: #451
closes: #452
closes: #453
closes: #454

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing behavior to change)
• Refactor (no behavior change)
• Docs / CI / tooling

How was it tested?

• Unit tests added/updated
• E2E test added/updated
• Manual verification steps below

Comprehensive unit test suites were implemented covering all four feature modules:

1. src/community-events/community-events.service.spec.ts: Tests event creation, scheduled lifecycle transitions, contribution tracking, milestone unlocking, leaderboard ranking, and reward claiming.
2. src/inventory/inventory.service.spec.ts: Tests item addition, automated stack management, max inventory slot limits enforcement, item removal/consumption, equipping, sorting, and filtering.
3. src/battle-pass/battle-pass.service.spec.ts: Tests season management, XP progression, automated tier advancement, dual-track (free/premium) reward claims, retroactive unlocks on premium pass purchase, and season analytics.
4. src/account/account-management.service.spec.ts: Tests progression reset requests with pre-reset backup snapshots, 5-minute cooldown safety token confirmation, reset cancellation, external account linking/unlinking, and audit trail logging.

Checklist

• npm run lint passes
• npm run format:check passes (run npm run format if not)
• npm run typecheck passes
• npm test passes
• I added/updated tests for the change
• I updated relevant docs (README, JSDoc, comments)
• I added a changeset / migration if schema changed
• I read CONTRIBUTING.md

Screenshots / Logs

All 4 modules designed with complete TypeORM entities, DTOs with class-validator / Swagger OpenAPI metadata, service business logic with cron scheduling, and controllers:

• CommunityEventsModule: @Cron lifecycle management, milestone evaluation, participation verification
• InventoryModule: Category slot limits, auto-stacking, item filtering/sorting
• BattlePassModule: Dual free/premium reward tracks, retroactive reward distribution
• AccountModule: Tokenized progression resets, snapshot recovery, provider linking, audit logging

Risk & rollout

Low risk; all features are implemented as modular entities, services, and endpoints (/community-events, /inventory, /battle-pass, and new sub-routes on /account), without modifying or breaking existing database schema or endpoints.