feat(sprint4): achievements, community goals, hall of fame, profile

4 modules: achievement (15 succès, 5 catégories, 3 paliers), community
(objectifs collectifs + boosts globaux), halloffame (classement mensuel),
profile (titre actif + badges + % progression).

Event-driven: combat/forge/craft émettent des events via @nestjs/event-emitter.
Character entity: +activeTitle, +totalGoldEarned.
Seeds: 15 achievements + 3 community goals.

package.json

@@ -19,6 +19,7 @@
     "@nestjs/common": "^10.0.0",
     "@nestjs/config": "^3.0.0",
     "@nestjs/core": "^10.0.0",
+    "@nestjs/event-emitter": "^3.0.1",
     "@nestjs/jwt": "^10.0.0",
     "@nestjs/platform-express": "^10.0.0",
     "@nestjs/throttler": "^5.0.0",