Add browser Python editor with Pyodide, user auth, and workspace API

- FastAPI serves static UI, file CRUD under code/ and read-only lib/
- Pyodide worker runs Python and Jedi completions in the browser
- SQLite accounts: login/register, session cookies, superuser user management
- Optional EDITOR_API_KEY, AUTH_* env vars, .env.example
- Pipenv, pytest, Selenium smoke test, README

Made-with: Cursor

Pipfile

@@ -0,0 +1,25 @@
+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[dev-packages]
+pytest = "*"
+pytest-cov = "*"
+httpx = "*"
+selenium = "*"
+
+[packages]
+fastapi = "*"
+uvicorn = "*"
+sqlalchemy = "*"
+bcrypt = "*"
+
+[requires]
+python_version = "3.12"
+
+[scripts]
+dev = "uvicorn app:app --app-dir src --reload --port 8080"
+test = "bash -lc 'cd src && PYTHONPATH=. pytest ../tests'"
+test-integration = "bash -lc 'cd src && PYTHONPATH=. pytest ../tests -m integration'"
+test-selenium = "bash -lc 'cd src && PYTHONPATH=. pytest ../tests -m selenium -v'"