feat(other-models): announce the feature only when folders are available

Other Models management is opt-in and its folders come from
folder_paths.get_folder_paths(). In plugin mode ComfyUI registers vae,
upscale_models, text_encoders, clip_vision and controlnet out of the box, so
enabling the feature works immediately. Standalone only knows the keys present
in settings.json.folder_paths, and that file is edited by hand - there is no UI
for those keys - so a standalone user who followed the announcement banner
reached "Enable Other Models" and then an empty page.

Gate the announcement on the capability instead of on how the process was
started:

- Config.get_other_models_availability() probes every canonical other key
  (legacy clip collapses into text_encoders where the host exposes
  map_legacy) and reports which sub_types resolve to a folder that exists on
  disk. It deliberately ignores enable_other_models: the question is "could
  this work here at all?". An empty folder counts, because CivitAI downloads
  can target it.
- /api/lm/settings exposes it as the derived, non-persisted
  other_models_paths_available flag; a probe failure yields null and the
  banner fails open.
- BannerService only registers the announcement when the flag is not false.
  `=== false` (not falsy) keeps a cached/older payload working, and nothing is
  written to dismissed_banners, so the banner can return once folders exist.
- The Other page grows an "enabled but nothing to scan" empty state driven by
  config.other_roots, showing the settings.json snippet for standalone and a
  pointer to ComfyUI model paths otherwise, plus an Open Settings action. It
  also covers the corner where only a non-default sub_type has a folder.

Translate the six other.noPaths.* keys into all nine locales and record the
new "folder key" / "on disk" terminology in the i18n guidelines.

Backend tests and pytest tests/i18n could not run in this environment (no
pytest/platformdirs); the probe was exercised against a stubbed folder_paths.
Frontend: 120 files / 1101 JS tests passed.

tests/frontend/pages/otherDisabledPage.test.js

@@ -22,7 +22,10 @@ describe('Other Models disabled page', () => {
         vi.resetModules();
         vi.clearAllMocks();
         initializeAppMock.mockResolvedValue(undefined);
-        document.body.innerHTML = '<button id="enableOtherModelsBtn"></button>';
+        document.body.innerHTML = [
+            '<button id="enableOtherModelsBtn"></button>',
+            '<button id="openOtherModelsSettingsBtn"></button>',
+        ].join('');
 
         Object.defineProperty(window, 'location', {
             value: { ...originalLocation, reload: vi.fn() },
@@ -43,12 +46,24 @@ describe('Other Models disabled page', () => {
             writable: true,
         });
         delete global.fetch;
+        delete window.modalManager;
     });
 
     it('boots the shared app core so the header stays usable', () => {
         expect(initializeAppMock).toHaveBeenCalledTimes(1);
     });
 
+    it('opens the Library settings from the no-folders state', () => {
+        const showModal = vi.fn();
+        window.modalManager = { showModal };
+
+        document.getElementById('openOtherModelsSettingsBtn').dispatchEvent(
+            new MouseEvent('click', { bubbles: true }),
+        );
+
+        expect(showModal).toHaveBeenCalledWith('settingsModal');
+    });
+
     it('enables Other Models through the settings API and reloads', async () => {
         global.fetch = vi.fn().mockResolvedValue({
             ok: true,