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

version/version.go

@@ -0,0 +1,10 @@
+// Package version holds build-time version information injected via ldflags.
+package version
+
+// Version and Commit are set at build time via:
+//
+//	-ldflags "-X github.com/ryanhamamura/games/version.Version=... -X github.com/ryanhamamura/games/version.Commit=..."
+var (
+	Version = "dev"
+	Commit  = "unknown"
+)