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

scripts/generate-build-info.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+
+# Generate build information for Hugo
+# This script collects git information and build metadata
+
+set -euo pipefail
+
+# Create data directory if it doesn't exist
+mkdir -p data
+
+# Get git information
+GIT_COMMIT=$(git rev-parse HEAD 2>/dev/null || echo "unknown")
+GIT_COMMIT_SHORT=$(git rev-parse --short HEAD 2>/dev/null || echo "unknown")
+GIT_BRANCH=$(git rev-parse --abbrev-ref HEAD 2>/dev/null || echo "unknown")
+GIT_TAG=$(git describe --tags --exact-match 2>/dev/null || echo "")
+GIT_DIRTY=""
+
+# Check if working directory is dirty
+if git diff-index --quiet HEAD -- 2>/dev/null; then
+    GIT_DIRTY="false"
+else
+    GIT_DIRTY="true"
+fi
+
+# Get build information
+BUILD_TIME=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
+BUILD_TIME_HUMAN=$(date -u +"%Y-%m-%d %H:%M UTC")
+BUILD_USER=$(whoami 2>/dev/null || echo "unknown")
+BUILD_HOST=$(hostname 2>/dev/null || echo "unknown")
+
+# Create JSON file for Hugo
+cat > data/build_info.json << EOF
+{
+  "git_commit": "${GIT_COMMIT}",
+  "git_commit_short": "${GIT_COMMIT_SHORT}",
+  "git_branch": "${GIT_BRANCH}",
+  "git_tag": "${GIT_TAG}",
+  "git_dirty": ${GIT_DIRTY},
+  "build_time": "${BUILD_TIME}",
+  "build_time_human": "${BUILD_TIME_HUMAN}",
+  "build_user": "${BUILD_USER}",
+  "build_host": "${BUILD_HOST}"
+}
+EOF
+
+echo "✓ Build info generated: data/build_info.json"
+echo "  Git: ${GIT_BRANCH}@${GIT_COMMIT_SHORT}${GIT_TAG:+ (${GIT_TAG})}"
+echo "  Built: ${BUILD_TIME_HUMAN} by ${BUILD_USER}"