fix: 完善首页和详情页国际化实现

- 首页 hero 区域标题和描述使用 i18n 翻译
- 首页 "BROWSE BY TAGS" 和 "FEATURED PROJECTS" 使用 i18n 翻译
- 详情页 "BACK TO PROJECTS" 使用 i18n 翻译
- 添加缺失的中英文翻译键

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/messages/en.json

@@ -15,9 +15,17 @@
     "browseByTag": "Browse by Tag",
     "searchPlaceholder": "Search AI projects...",
     "metaTitle": "Agent Park - AI Project Navigator",
-    "metaDescription": "Discover and explore quality AI projects from across the web"
+    "metaDescription": "Discover and explore quality AI projects from across the web",
+    "heroTitle": "AI PROJECT",
+    "heroTitle2": "NAVIGATOR",
+    "heroDescription": "Discover and explore high-quality AI projects from across the web. Curated for developers and enthusiasts.",
+    "browseByTagsSection": "BROWSE BY TAGS",
+    "featuredProjectsSection": "FEATURED PROJECTS",
+    "viewAll": "VIEW ALL",
+    "viewAllProjects": "VIEW ALL PROJECTS"
   },
   "project": {
+    "backToProjects": "BACK TO PROJECTS",
     "details": "Project Details",
     "externalLinks": "External Links",
     "viewProject": "View Project",