Add PostgreSQL memory system for persistent user and conversation storage

- Add PostgreSQL database with SQLAlchemy async support
- Create models: User, UserFact, UserPreference, Conversation, Message, Guild, GuildMember
- Add custom name support so bot knows 'who is who'
- Add user facts system for remembering things about users
- Add persistent conversation history that survives restarts
- Add memory commands cog (!setname, !remember, !whatdoyouknow, !forgetme)
- Add admin commands (!setusername, !teachbot)
- Set up Alembic for database migrations
- Update docker-compose with PostgreSQL service
- Gracefully falls back to in-memory storage when DB not configured

src/daemon_boyfriend/services/__init__.py

@@ -2,14 +2,22 @@
 
 from .ai_service import AIService
 from .conversation import ConversationManager
+from .database import DatabaseService, db, get_db
+from .persistent_conversation import PersistentConversationManager
 from .providers import AIResponse, ImageAttachment, Message
 from .searxng import SearXNGService
+from .user_service import UserService
 
 __all__ = [
     "AIService",
     "AIResponse",
+    "ConversationManager",
+    "DatabaseService",
     "ImageAttachment",
     "Message",
-    "ConversationManager",
+    "PersistentConversationManager",
     "SearXNGService",
+    "UserService",
+    "db",
+    "get_db",
 ]