Refactor database initialization and remove Alembic migrations

- Removed legacy Alembic migration files and consolidated schema management into a new Pydantic-backed initializer (`scripts/init_db.py`).
- Updated `main.py` to ensure the new DB initializer runs on startup, maintaining idempotency.
- Adjusted session management in `config/database.py` to prevent DetachedInstanceError.
- Introduced new enums in `models/enums.py` for better organization and clarity.
- Refactored various models to utilize the new enums, improving code maintainability.
- Enhanced middleware to handle JSON validation more robustly, ensuring non-JSON requests do not trigger JSON errors.
- Added tests for middleware and enums to ensure expected behavior and consistency.
- Updated changelog to reflect significant changes and improvements.

changelog.md

@@ -3,6 +3,7 @@
 ## 2025-11-12
 
 - Switched `models/performance_metric.py` to reuse the shared declarative base from `config.database`, clearing the SQLAlchemy 2.0 `declarative_base` deprecation warning and verifying repository tests still pass.
+- Replaced the Alembic migration workflow with the idempotent Pydantic-backed initializer (`scripts/init_db.py`), added a guarded reset utility (`scripts/reset_db.py`), removed migration artifacts/tooling (Alembic directory, config, Docker entrypoint), refreshed the container entrypoint to invoke `uvicorn` directly, and updated installation/architecture docs plus the README to direct developers to the new seeding/reset flow.
 - Eliminated Bandit hardcoded-secret findings by replacing literal JWT tokens and passwords across auth/security tests with randomized helpers drawn from `tests/utils/security.py`, ensuring fixtures still assert expected behaviours.
 - Centralized Bandit configuration in `pyproject.toml`, reran `bandit -c pyproject.toml -r calminer tests`, and verified the scan now reports zero issues.
 - Updated `.github/instructions/TODO.md` and `.github/instructions/DONE.md` to reflect the completed security scan remediation workflow.
@@ -13,6 +14,7 @@
 
 ## 2025-11-11
 
+- Collapsed legacy Alembic revisions into `alembic/versions/00_initial.py`, removed superseded migration files, and verified the consolidated schema via SQLite upgrade and Postgres version stamping.
 - Implemented base URL routing to redirect unauthenticated users to login and authenticated users to dashboard.
 - Added comprehensive end-to-end tests for login flow, including redirects, session handling, and error messaging for invalid/inactive accounts.
 - Updated header and footer templates to consistently use `logo_big.png` image instead of text logo, with appropriate CSS styling for sizing.