fix: move Dockerfile back to root for HF Spaces compatibility

HF Spaces requires Dockerfile at repo root. COPY paths reference backend/
so repo structure is preserved. render.yaml updated accordingly.

README.md

@@ -5,7 +5,6 @@ colorFrom: purple
 colorTo: blue
 sdk: docker
 app_port: 8000
-dockerfile_path: backend/Dockerfile
 pinned: false
 ---
 

render.yaml

@@ -2,7 +2,7 @@ services:
   - type: web
     name: eumora-api
     runtime: docker
-    dockerfilePath: ./backend/Dockerfile
+    dockerfilePath: ./Dockerfile
     plan: standard          # 4 GB RAM — required for DeBERTa inference
     numInstances: 1
     healthCheckPath: /health