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

server/__tests__/ai-tool-jobs.test.js

@@ -371,7 +371,12 @@ describe("jobs", () => {
     }
   });
 
-  it("update-all runs the badged npm tools and every self updater", async () => {
+  it("update-all runs every npm-managed tool and every self updater, asking npm no version", async () => {
+    let viewed = 0;
+    versions.__setExec(async (_f, args) => {
+      if (args[0] === "view") viewed++;
+      return { stdout: args[0] === "prefix" ? `${prefix}\n` : "1.0.0\n" };
+    });
     await jobs.startUpdateAll();
     const done = await settle();
     assert.equal(done.status, "ok");
@@ -379,5 +384,6 @@ describe("jobs", () => {
       spawned.map((s) => s.argv.slice(1).join(" ")),
       ["install -g npm-tool@latest", "update --yes"]
     );
+    assert.equal(viewed, 0);
   });
 });

server/__tests__/ai-tools-route.test.js

@@ -164,7 +164,7 @@ describe("install / update / icons", () => {
     const { body } = await request("GET", "/api/ai-tools");
     const codex = body.tools.find((t) => t.id === "codex");
     assert.deepEqual(codex.install, { kind: "npm", package: "@openai/codex" });
-    assert.deepEqual(codex.update, { kind: "npm" });
+    assert.deepEqual(codex.update, { kind: "self", args: ["update"] }); // standalone or npm
     assert.equal(body.catalog.source, "builtin");
   });