## Chat History
- Persist user and assistant messages to `chat_messages` table after every
chat interaction (both LLM-generated and direct/greeting responses)
- GET /room/{room_id} now returns full chat history via eager-loaded
`messages` relation, sorted by created_at ascending
- Added `ChatMessageResponse` Pydantic model to room response schema
## Room Soft Delete
- Added `status` column (active | inactive) to Room model
- GET /rooms/{user_id} filters to only return active rooms
- New DELETE /room/{room_id}?user_id=... endpoint: sets status to inactive
instead of physically deleting the row (data preserved for audit/recovery)
- Added idempotent migration in init_db.py:
ALTER TABLE rooms ADD COLUMN IF NOT EXISTS status VARCHAR NOT NULL DEFAULT 'active'
## User Migration: MongoDB → PostgreSQL
- Migrated user storage from MongoDB to PostgreSQL (User model added to models.py)
- get_user() now queries PostgreSQL via AsyncSessionLocal instead of MongoClient
- Replaced all emarcal…
