chore: remove blog, open-source and news sections

- Delete the blogs, opensource-projects and notifications trees
- Drop their nav entries and i18n keys
- Point the nav at the new open-source site instead
- Drop the opensource-projects sitemap priority

i18n.json

@@ -123,50 +123,10 @@
     "en-gb": "Services",
     "zh-hans": "定制服务"
   },
-  "nav.insights": {
-    "en-gb": "Insights",
-    "zh-hans": "技术洞察"
-  },
-  "nav.news": {
-    "en-gb": "News",
-    "zh-hans": "企业动态"
-  },
   "nav.opensource": {
     "en-gb": "Open Source",
     "zh-hans": "开源生态"
   },
-  "opensource.group.libraries": {
-    "en-gb": "Libraries & Toolkits",
-    "zh-hans": "库与工具包"
-  },
-  "opensource.group.applications": {
-    "en-gb": "Full-Stack Applications",
-    "zh-hans": "全栈应用"
-  },
-  "opensource.group.tools": {
-    "en-gb": "Developer Tools",
-    "zh-hans": "开发者工具"
-  },
-  "insights.group.frontend": {
-    "en-gb": "Frontend",
-    "zh-hans": "前端"
-  },
-  "insights.group.backend": {
-    "en-gb": "Backend & Data",
-    "zh-hans": "后端与数据"
-  },
-  "insights.group.devops": {
-    "en-gb": "DevOps & Infrastructure",
-    "zh-hans": "运维与基础设施"
-  },
-  "insights.group.practice": {
-    "en-gb": "Engineering Practice",
-    "zh-hans": "工程实践"
-  },
-  "insights.group.tooling": {
-    "en-gb": "Tooling & Troubleshooting",
-    "zh-hans": "工具与疑难排查"
-  },
   "footer.copyright": {
     "en-gb": "© 2026 Changsha OnixByte Technology Co., Ltd. All rights reserved.",
     "zh-hans": "© 2026 长沙曜珀科技有限公司 版权所有"