Add initial web editor app, CLI scripts, and test scaffolding.

This introduces the FastAPI editor implementation and related project setup so the app can be run and validated locally.

Made-with: Cursor

src/editor_app/main.py

@@ -0,0 +1,28 @@
+from fastapi import FastAPI
+from fastapi.staticfiles import StaticFiles
+
+from editor_app.config import STATIC_DIR, WORKSPACE_ROOT
+from editor_app.routers.files import router as files_router
+from editor_app.routers.frontend import router as frontend_router
+from editor_app.routers.python_exec import router as python_router
+
+
+def create_app() -> FastAPI:
+    app = FastAPI()
+    app.mount("/static", StaticFiles(directory=str(STATIC_DIR)), name="static")
+    app.include_router(frontend_router)
+    app.include_router(files_router)
+    app.include_router(python_router)
+
+    @app.on_event("startup")
+    async def run_configured_startup_script() -> None:
+        from editor_app.services import python_runner
+
+        (WORKSPACE_ROOT / "lib").mkdir(parents=True, exist_ok=True)
+        python_runner.run_startup_script_if_configured()
+
+    return app
+
+
+app = create_app()
+