refactor: Overhaul project structure and role management

This commit implements the first phase of the new architectural vision for the Talia Bot.

Key changes include:
- Renamed the main application directory from `app` to `talia_bot` and updated all associated imports and configurations (`Dockerfile`, tests).
- Replaced the static, `.env`-based permission system with a dynamic, database-driven role management system.
- Introduced a `db.py` module to manage a SQLite database (`users.db`) for user persistence.
- Updated `identity.py` to fetch roles ('admin', 'crew', 'client') from the database.
- Rewrote the `README.md` and `.env.example` to align with the new project specification.
- Refactored the LLM module into the new `modules` structure.

test_calendar_debug.py

@@ -3,9 +3,9 @@ import sys
 import os
 
 # Add app directory to path
-sys.path.append(os.path.join(os.getcwd(), 'app'))
+sys.path.append(os.path.join(os.getcwd(), 'talia_bot'))
 
-from google_calendar import get_events
+from modules.calendar import get_events
 from config import CALENDAR_ID
 
 def test_get_events():