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

CLAUDE.md

@@ -11,9 +11,12 @@ pip install -r requirements.txt
 # Run the bot (requires .env with DISCORD_TOKEN and AI provider key)
 python -m daemon_boyfriend
 
-# Run with Docker
+# Run with Docker (includes PostgreSQL)
 docker-compose up -d
 
+# Run database migrations
+alembic upgrade head
+
 # Syntax check all Python files
 python -m py_compile src/daemon_boyfriend/**/*.py
 ```
@@ -33,9 +36,25 @@ The AI system uses a provider abstraction pattern:
 ### Cog System
 Discord functionality is in `cogs/`:
 - `ai_chat.py` - `@mention` handler (responds when bot is mentioned)
+- `memory.py` - Memory management commands (`!setname`, `!remember`, etc.)
+- `status.py` - Bot health and status commands
 
 Cogs are auto-loaded by `bot.py` from the `cogs/` directory.
 
+### Database & Memory System
+The bot uses PostgreSQL for persistent memory (optional, falls back to in-memory):
+- `models/` - SQLAlchemy models (User, UserFact, Conversation, Message, Guild, GuildMember)
+- `services/database.py` - Connection pool and async session management
+- `services/user_service.py` - User CRUD, custom names, facts management
+- `services/persistent_conversation.py` - Database-backed conversation history
+- `alembic/` - Database migrations
+
+Key features:
+- Custom names: Set preferred names for users so the bot knows "who is who"
+- User facts: Bot remembers things about users (hobbies, preferences, etc.)
+- Persistent conversations: Chat history survives restarts
+- Conversation timeout: New conversation starts after 60 minutes of inactivity
+
 ### Configuration
 All config flows through `config.py` using pydantic-settings. The `settings` singleton is created at module load, so env vars must be set before importing.
 
@@ -47,13 +66,31 @@ The bot can search the web for current information via SearXNG:
 - Configured via `SEARXNG_URL`, `SEARXNG_ENABLED`, and `SEARXNG_MAX_RESULTS` env vars
 
 ### Key Design Decisions
-- `ConversationManager` stores per-user chat history in memory with configurable max length
+- `PersistentConversationManager` stores conversations in PostgreSQL when `DATABASE_URL` is set
+- `ConversationManager` is the in-memory fallback when database is not configured
 - Long AI responses are split via `split_message()` in `ai_chat.py` to respect Discord's 2000 char limit
 - The bot responds only to @mentions via `on_message` listener
 - Web search uses AI to decide when to search, avoiding unnecessary API calls for general knowledge questions
+- User context (custom name + known facts) is included in AI prompts for personalized responses
 
 ## Environment Variables
 
 Required: `DISCORD_TOKEN`, plus one of `OPENAI_API_KEY`, `OPENROUTER_API_KEY`, `ANTHROPIC_API_KEY`, or `GEMINI_API_KEY` depending on `AI_PROVIDER` setting.
 
-Optional: `SEARXNG_URL` for web search capability.
+Optional:
+- `DATABASE_URL` - PostgreSQL connection string (e.g., `postgresql+asyncpg://user:pass@host:5432/db`)
+- `POSTGRES_PASSWORD` - Used by docker-compose for the PostgreSQL container
+- `SEARXNG_URL` - SearXNG instance URL for web search capability
+
+## Memory Commands
+
+User commands:
+- `!setname <name>` - Set your preferred name
+- `!clearname` - Reset to Discord display name
+- `!remember <fact>` - Tell the bot something about you
+- `!whatdoyouknow` - See what the bot remembers about you
+- `!forgetme` - Clear all facts about you
+
+Admin commands:
+- `!setusername @user <name>` - Set name for another user
+- `!teachbot @user <fact>` - Add a fact about a user