refactor(config): use Vite proxy for API requests and change backend port

- Configure Vite dev server to proxy /v1 requests to backend
- Change backend port from 8000 to 8001
- Simplify API URLs to relative paths instead of absolute localhost URLs
- Increase debounce delay from 500ms to 1000ms for better stability
- Update README documentation to reflect all changes

backend/main.py

@@ -109,4 +109,4 @@ async def ocr_image(request: OCRRequest):
 
 if __name__ == "__main__":
     import uvicorn
-    uvicorn.run(app, host="0.0.0.0", port=8000)
+    uvicorn.run(app, host="0.0.0.0", port=8001)