feat(ui): add git version info display in header

- Display current branch/tag and commit hash in navbar center
- Show dirty working directory indicator with yellow badge
- Add automatic build info generation in Task workflow
- Include build timestamp and user information
- Style with responsive design (hidden on mobile)
- Add .gitignore entries for generated build artifacts

.gitignore

@@ -13,6 +13,12 @@ tmp/
 # devbox
 .devbox/
 
+# Task cache
+.task/
+
+# Generated build data
+data/
+
 # IDE
 .vscode/
 .idea/