feat: Integrated SQLite database and project history into B2B Marketing Assistant

- market_db_manager.py: Made DB_PATH configurable via environment variable.

- Dockerfile.b2b: Included market_db_manager.py in the B2B container image.

- docker-compose.yml: Configured separate DB paths and volumes for Market Intel and B2B Assistant.

- B2B Server: Added API routes for project management (list, load, save, delete).

- B2B UI: Implemented auto-save and a 'Project History' modal for loading past runs.

market_db_manager.py

@@ -4,7 +4,7 @@ import os
 import uuid
 from datetime import datetime
 
-DB_PATH = "/app/market_intelligence.db"
+DB_PATH = os.environ.get("DB_PATH", "/app/market_intelligence.db")
 
 def get_db_connection():
     conn = sqlite3.connect(DB_PATH)