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.

README.md

@@ -8,4 +8,6 @@ The system is designed to help mining companies make informed decisions by simul
 
 ## Documentation & quickstart
 
-This repository contains only code. See detailed developer and architecture documentation in the [Docs](https://git.allucanget.biz/allucanget/calminer-docs) repository.
+- Detailed developer, architecture, and operations guides live in the companion [calminer-docs](../calminer-docs/) repository.
+- For a local run, create a `.env` (see `.env.example`), install requirements, then execute `python -m scripts.init_db` followed by `uvicorn main:app --reload`. The initializer is safe to rerun and seeds demo data automatically.
+- To wipe and recreate the schema in development, run `CALMINER_ENV=development python -m scripts.reset_db` before invoking the initializer again.