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

src/editor_app/routers/frontend.py

@@ -0,0 +1,26 @@
+from fastapi import APIRouter
+from fastapi.responses import FileResponse
+
+from editor_app.config import STATIC_DIR
+
+router = APIRouter()
+
+
+@router.get("/")
+async def serve_home():
+    return FileResponse(STATIC_DIR / "home.html")
+
+
+@router.get("/editor")
+async def serve_frontend():
+    return FileResponse(STATIC_DIR / "index.html")
+
+
+@router.get("/login")
+async def serve_login():
+    return FileResponse(STATIC_DIR / "login.html")
+
+
+@router.get("/register")
+async def serve_register():
+    return FileResponse(STATIC_DIR / "register.html")