Make VITE_BACKEND_URL configurable via env

Allow the frontend backend URL to be overridden without editing files. docker-compose.yml now injects VITE_BACKEND_URL using shell parameter expansion with a default (http://localhost:11006). The frontend Dockerfile removes the hardcoded ARG default and exports ARG as ENV so the build-arg can supply the value.

Author: david-randoll

examples/docker-compose.yml

@@ -8,7 +8,7 @@ services:
     build:
       context: ./frontend
       args:
-        VITE_BACKEND_URL: http://localhost:11006
+        VITE_BACKEND_URL: ${VITE_BACKEND_URL:-http://localhost:11006}
     ports:
       - "11007:11007"
     depends_on:

examples/frontend/Dockerfile

@@ -4,7 +4,7 @@ WORKDIR /app
 COPY package*.json ./
 RUN npm install
 COPY . .
-ARG VITE_BACKEND_URL=http://localhost:11006
+ARG VITE_BACKEND_URL
 ENV VITE_BACKEND_URL=$VITE_BACKEND_URL
 RUN npm run build