feat: display app version in UI footer

- Add version package with build-time variables
- Inject version via ldflags in Dockerfile using git describe
- Show version in footer on every page
- Log version and commit on server startup

docker-compose.yml

@@ -1,6 +1,10 @@
 services:
   games:
-    build: .
+    build:
+      context: .
+      args:
+        VERSION: ${VERSION:-dev}
+        COMMIT: ${COMMIT:-unknown}
     container_name: games
     restart: unless-stopped
     ports: