Replace Alembic with plain SQL schema

- Fix scalar_first() bug in persistent_conversation.py (use scalars().first())
- Add schema.sql with all 7 tables (users, user_preferences, user_facts, guilds, guild_members, conversations, messages)
- Update database.py to run schema.sql on startup
- Remove Alembic directory and configuration
- Remove alembic from requirements.txt

src/daemon_boyfriend/services/database.py

@@ -2,15 +2,19 @@
 
 import logging
 from contextlib import asynccontextmanager
+from pathlib import Path
 from typing import AsyncGenerator
 
+from sqlalchemy import text
 from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 
 from daemon_boyfriend.config import settings
-from daemon_boyfriend.models.base import Base
 
 logger = logging.getLogger(__name__)
 
+# Path to schema.sql (project root)
+SCHEMA_PATH = Path(__file__).parent.parent.parent.parent / "schema.sql"
+
 
 class DatabaseService:
     """Manages database connections and sessions."""
@@ -62,13 +66,24 @@ class DatabaseService:
             logger.info("Database connection closed")
 
     async def create_tables(self) -> None:
-        """Create all tables (for development/testing)."""
+        """Create all tables from schema.sql."""
         if not self._engine:
             raise RuntimeError("Database not initialized")
 
+        if not SCHEMA_PATH.exists():
+            logger.warning(f"schema.sql not found at {SCHEMA_PATH}, skipping table creation")
+            return
+
+        schema_sql = SCHEMA_PATH.read_text()
+
         async with self._engine.begin() as conn:
-            await conn.run_sync(Base.metadata.create_all)
-        logger.info("Database tables created")
+            # Execute each statement separately (PostgreSQL doesn't like multiple in one)
+            for statement in schema_sql.split(";"):
+                statement = statement.strip()
+                if statement and not statement.startswith("--"):
+                    await conn.execute(text(statement))
+
+        logger.info("Database tables created from schema.sql")
 
     @asynccontextmanager
     async def session(self) -> AsyncGenerator[AsyncSession, None]:

src/daemon_boyfriend/services/persistent_conversation.py

@@ -52,7 +52,7 @@ class PersistentConversationManager:
         stmt = stmt.order_by(Conversation.last_message_at.desc())
 
         result = await self._session.execute(stmt)
-        conversation = result.scalar_first()
+        conversation = result.scalars().first()
 
         if conversation:
             logger.debug(