Refactor Alembic configuration and update Docker setup

- Removed the `alembic.ini` file and migrated its configuration to `pyproject.toml` under `[tool.alembic]`, enhancing project organization.
- Updated the `Dockerfile` to copy `pyproject.toml` instead of `alembic.ini`, ensuring the new configuration is utilized during the build process.
- Modified `entrypoint.sh` to use the new Alembic configuration from `pyproject.toml` for database migrations.
- Updated README documentation to reflect the new Alembic configuration and usage instructions.

entrypoint.sh

@@ -4,7 +4,7 @@ set -e
 mkdir -p /app/data
 chown botuser:botuser /app/data
 # Apply Alembic migrations (runs as root, creates DB in /app/data)
-alembic upgrade head
+alembic -c pyproject.toml upgrade head
 # Ensure new DB file is owned by botuser so the app can write
 chown -R botuser:botuser /app/data
 # Run the app as botuser