feat(ui): AI Tools modal, one-button lane tool picker, AgentHub settings in Overview, markdown preview

- AI Tools moves from a Settings section into a modal behind a button at the
  Settings tab bar's right edge (AiToolsModal, `actions` on PageTabs,
  /settings#ai-tools); rows get an enable switch, Default badge, and an
  Update button for every tool whose catalog names an updater (no version
  lookup on open); not-installed tools fold behind a disclosure, a finished
  job's log folds to one line; shared AiToolIcon
- codex updates through its own `codex update`, openclaw/hermes gain
  `update --yes`; update-all runs every installed updater and skips an npm
  one only when npm does not manage the binary
- Add-lane tool picker is one button showing the chosen tool that opens the
  enabled tools as buttons
- Claude Code / Codex AgentHub sub-tab folded into Overview (home editor,
  hooks, pricing); the path list drops CLAUDE_HOME/CODEX_HOME;
  HomeDirSetting shows the saved value only while the field differs
- Preview/Raw toggle for markdown files in the config FileViewer and the
  Changes panel's whole-file view (MarkdownPreview: react-markdown +
  remark-gfm, raw HTML never run, frontmatter as a code block)
- docs and the CLAUDE.md marker updated

client/src/i18n/locales/vi/ccConfig.json

@@ -24,8 +24,7 @@
     "hooks": "Hooks",
     "keybindings": "Phím tắt",
     "settings": "Cài đặt",
-    "memory": "Bộ nhớ",
-    "agenthub": "AgentHub"
+    "memory": "Bộ nhớ"
   },
   "overview": {
     "rootsTitle": "Thư mục gốc",
@@ -51,7 +50,9 @@
     "modified": "Đã sửa",
     "scopeLabel": "Phạm vi",
     "noFrontmatter": "Không có frontmatter",
-    "redactedNotice": "Các giá trị khớp /token|secret|password|key|auth/i đã được ẩn ở phía máy chủ."
+    "redactedNotice": "Các giá trị khớp /token|secret|password|key|auth/i đã được ẩn ở phía máy chủ.",
+    "preview": "Xem trước",
+    "raw": "Mã nguồn"
   },
   "skills": {
     "name": "Tên",