Fix API URL: use window.location.origin for Docker deployment

Dockerfile

@@ -13,6 +13,12 @@ RUN bun install --frozen-lockfile
 
 # Build static files (output lands in /app/frontend/dist)
 COPY frontend/ ./frontend/
+
+# For Docker deployment, frontend and backend share the same origin.
+# Patch client.ts to default to same-origin (window.location.origin) instead
+# of hardcoded 127.0.0.1:3900, so all API/WebSocket calls go to the right host.
+RUN sed -i "s|viteEnv.VITE_API_URL || \`http://127.0.0.1:\${_port}\`|viteEnv.VITE_API_URL || (typeof window !== 'undefined' \&\& window.location ? window.location.origin : '')|" /app/frontend/src/api/client.ts
+
 RUN bun run --cwd frontend build
 
 # ==========================================
@@ -31,7 +37,7 @@ ENV UV_SYSTEM_PYTHON=1
 ENV HF_HOME=$HOME/app/omnivoice_data/huggingface
 # Allow bare imports
 ENV PYTHONPATH=$HOME/app/backend
-# Allow all origins (HF Spaces serves frontend from same port, but iframe embedding needs *)
+# Allow all origins (HF Spaces iframe embedding)
 ENV OMNIVOICE_ALLOWED_ORIGINS="*"
 # Bind to 0.0.0.0 for Docker networking
 ENV OMNIVOICE_BIND_HOST="0.0.0.0"