API: serve FastAPI at root; mount UI at /app; add root index and /health alias for integration without proxy

app.py

@@ -258,6 +258,24 @@ def _require_auth(authorization: str | None = Header(default=None)):
         raise HTTPException(status_code=401, detail="Invalid token")
 
 
+@api.get("/")
+def root_index():
+    return {
+        "name": "Smile Changer API",
+        "status": "ok",
+        "ui": "/app",
+        "endpoints": {
+            "GET /health": "public health",
+            "GET /api/health": "public health (alias)",
+            "GET /api/ping": "auth check",
+            "GET /api/attributes": "list attributes",
+            "POST /api/edit": "generic edit",
+            "POST /api/edit/{attribute}": "edit by attribute name",
+        },
+        "auth": "set API_AUTH_TOKEN to require Authorization: Bearer <token> (except /health)",
+    }
+
+
 @api.get("/api/attributes")
 def list_attributes(_: None = Depends(_require_auth)):
     items = {}
@@ -367,8 +385,8 @@ _register_attribute_endpoint("/api/orange-hair-text", "Orange hair (text)")
 _register_attribute_endpoint("/api/blonde-hair-text", "Blonde hair (text)")
 
 
-# Mount Gradio on FastAPI and expose combined app
-app = gr.mount_gradio_app(api, demo, path="/")
+# Mount Gradio under /app and expose FastAPI at root for clean API base
+app = gr.mount_gradio_app(api, demo, path="/app")
 
 
 @GPU()