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

Taskfile.yml

@@ -15,6 +15,7 @@ tasks:
     desc: Build Hugo site
     deps:
       - deps:ensure-npm
+      - build:generate-info
     cmds:
       - "{{.HUGO_CMD}} --gc --minify"
 
@@ -22,13 +23,25 @@ tasks:
     desc: Build Hugo site for development
     deps:
       - deps:ensure-npm
+      - build:generate-info
     cmds:
       - "{{.HUGO_CMD}}"
 
+  build:generate-info:
+    desc: Generate build information (git commit, version, etc.)
+    sources:
+      - .git/HEAD
+      - .git/refs/**/*
+    generates:
+      - data/build_info.json
+    cmds:
+      - ./scripts/generate-build-info.sh
+
   serve:
     desc: Start Hugo dev server
     deps:
       - deps:ensure-npm
+      - build:generate-info
     cmds:
       - "{{.HUGO_CMD}} server"
 
@@ -56,6 +69,7 @@ tasks:
     desc: Test Hugo build
     deps:
       - deps:ensure-npm
+      - build:generate-info
     cmds:
       - "{{.HUGO_CMD}} --gc --minify --logLevel info"