feat(docker): add Firebase credentials volume to Docker Compose for OAuth integration

.gitignore

@@ -4,4 +4,5 @@
 *.gocache
 *.exe
 */dist
+*/secrets
 */node_modules

backend/Dockerfile

@@ -25,8 +25,10 @@ RUN --mount=type=cache,target=/root/.cache/go-build \
 FROM alpine:3.20
 # minimal tools for healthcheck + TLS roots + timezone
 RUN apk add --no-cache ca-certificates tzdata curl && \
-    adduser -D -H -u 10001 app
+    adduser -D -H -u 10001 app && \
+    mkdir -p /home/app && chown app:app /home/app
 USER app
+ENV HOME=/home/app
 WORKDIR /app
 
 COPY --from=builder /out/server /app/server

docker-compose.yml

@@ -65,6 +65,8 @@ services:
     entrypoint: ["/app/migrate"]
     env_file:
       - ./.env
+    volumes:
+      - ./backend/secrets/firebase_credentials.json:/secrets/firebase_credentials.json:ro
     depends_on:
       db:
         condition: service_healthy
@@ -83,6 +85,8 @@ services:
         condition: service_completed_successfully
     expose:
       - "8082"
+    volumes:
+      - ./backend/secrets/firebase_credentials.json:/secrets/firebase_credentials.json:ro
     restart: unless-stopped
     networks: [internal]
     healthcheck: