fix(custom-model): act on the draft review — unparseable onclick, unwrapped envelope, wrong-session apply, missing lock, no tests

Addresses every blocker, both majors, and all but one minor from the
maintainer's review of the draft PR.

Blockers:

1. Every generated inline onclick was unparseable. JSON.stringify's own
   double quotes terminated the double-quoted HTML attribute at the first
   one, leaving btn.onclick null on every picker entry and every Discover/
   Edit/Delete button. Fixed with escapeHtml(JSON.stringify(...)) per
   argument, the same idiom deleteCase's onclick already uses four lines
   away in session-ui.js. This also closes the live-HTML-injection route
   through modelId (server-controlled, from the endpoint's own /v1/models
   reply): with quoting intact, a `>` inside it can no longer terminate the
   <button> tag early.
2. GET /api/model-endpoints wraps its body in the {success,data} envelope
   like every other /api route (server.ts's preSerialization hook applies
   to arrays too), so Array.isArray(hosts) was always false in production
   and the picker/settings panel silently saw nothing. Both call sites now
   go through _apiJson(), which already exists for exactly this.
3. A failed or declined run*() (missing CLI, isBusy, a caught exception)
   returns normally without ever changing activeSessionId, so the apply
   step used to silently re-point and restart whatever session the user was
   already looking at. runCustomModelEntry() now snapshots activeSessionId
   before the launch and requires it to have actually changed.

Majors:

4. Routes the launch through run() itself via a temporary _runMode swap
   (never persisted — setRunMode() would sync it to the server) instead of
   a parallel hardcoded dispatch table, so a custom-model launch now holds
   the same _runInFlight lock every other Run click gets. This also
   resolves the "hardcoded runners map contradicts the PR's own design"
   minor: dispatch is run()'s own, so a CLI whose customModelInjection
   recipe lands later needs no update here.
5. New test/custom-model-run-menu-ui.test.ts drives the real session-ui.js
   against a JSDOM window (runScripts:"dangerously" — this JSDOM only ever
   parses markup this module generated itself) for exactly the DOM-level
   facts the review said needed no Playwright and no tmux: a generated
   button's onclick genuinely compiles and fires, a dangerous modelId never
   produces a live element, the envelope unwrap works, the session-changed
   guard holds, run() actually gets called (proving the in-flight lock
   engages), and _runMode is restored afterward. Confirmed against the
   pre-fix code first (reproduces btn.onclick === null exactly) so this
   isn't a vacuous pass. Plus new tests in custom-model-routes.test.ts and
   render-index-html.test.ts for the other fixes below.

Minors:

- Generated entries now filter through isCliAvailable(), matching
  _refreshRunModeAvailability's own gating of the stock entries.
- The CRUD panel is now gated on customModelEndpointsEnabled
  (applyCustomModelEndpointsVisibility(), wired to the toggle's onchange
  and to settings-modal open) instead of always rendering; the endpoint GET
  no longer fires unconditionally either.
- API keys are never handed back to the browser on GET, POST or PUT —
  redactApiKey() replaces the field with a computed apiKeySet: boolean, and
  a PUT with no apiKey now keeps the stored one server-side
  (applyStoredApiKey()) instead of the client resending a value it was
  never given. New tests cover both directions (kept vs. replaced) by
  observing the actual auth header a subsequent discovery request sends.
- "+ Add endpoint" hides for a non-admin in multi-user mode
  (_applyCustomModelAdminGate(), also wired to admin-ui.js's codeman:me
  event, since the real role can resolve after settings were first opened)
  — endpoint writes were already admin-only server-side, but the button
  used to render for everyone and eat a 403.
- design doc (custom-model-endpoints-plan.md §4) now says up front that its
  toolbar-button design was superseded by the Run-menu picker.
- docs/api-reference.md gained a Custom Model Endpoints section (every
  route, the apiKeySet/defaultModelId contract, the restart mechanics).
- Wiki page now covers un-pointing a session (curl/delete, no UI yet) and
  that the picker is desktop-only for now.
- .set-inline-form uses --control-bg instead of a hardcoded black alpha
  (CLAUDE.md already records that exact literal turning the settings
  preview into a grey slab on light skins), .run-mode-custom-models gets
  the same gap: 2px .run-mode-menu's own flex gap only applies one level
  up, and the index.html comment naming the wrong function is fixed.
- __codemanCustomModelClis's JSON is now escaped against a literal
  </script> (CliEntry.label is user-clis.json-settable, unlike
  __codemanCliAvailable's booleans-only payload) via a new exported
  escapeScriptJson(), pure and unit-tested without needing a WebServer.
- Added defaultModelId + the new /v1/model-endpoints routes to
  docs/api-reference.md; left the "no zh-CN for the new Models-section
  group" minor unaddressed only insofar as the wider Models section (task
  routing, thinking effort, etc.) has never had zh-CN coverage either —
  everything this PR itself introduces (labels, hints, button text, the
  Run-menu's "Custom Endpoints" header) IS translated in i18n.js.

Regression caught while fixing #4: the admin-gate's codeman:me listener is
a module-level document.addEventListener() call, which threw in
run-mode-ui.test.ts's minimal vm-context fake document and failed all 10
of that file's tests. Fixed with optional chaining before it ever reached
the branch this commit lands on; full targeted suite (route tests,
structural guards, every settings-ui.js-loading frontend test) reverified
green afterward.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RqZeHrRS6DYcGcGX2p9EwG

docs/custom-model-endpoints-plan.md

@@ -208,6 +208,14 @@ extra per-model configuration on Codeman's side at all.
 
 ### 4. Toolbar UI
 
+> **Superseded.** This section describes the toolbar-button design as originally
+> planned. What actually shipped is a Run-menu picker instead: one generated entry
+> per (capable harness, saved endpoint) pair directly in the existing `#runModeMenu`
+> dropdown, rather than a separate `#customModelBtn`/`#customModelMenu` surface. See
+> [`docs/custom-model-endpoints.md`](custom-model-endpoints.md#the-run-menu-picker)
+> for the current design; the sections below (session-restart mechanics, security)
+> remain accurate regardless of which UI calls the underlying route.
+
 - New header/toolbar button (e.g. `#customModelBtn`, `btn-toolbar
 btn-custom-model`), marker-hidden by default (`btn-custom-model--hidden`)
   and revealed by `applyHeaderVisibilitySettings()` only when