feat(editor): add gitmost bridge for listing spaces/pages and creating a page with a recording

Extend the window.gitmost native-host bridge with three methods that work
when no page is open, registered globally at the app-shell level (not in
page-editor.tsx) so the react-router navigate fn and the api-client are
available:

- listSpaces(): reuse getSpaces() -> [{id, name}], flags truncation.
- listPages({spaceId, parentPageId?}): reuse getSidebarPages()
  -> [{id, title, hasChildren}], first page only (truncated flag).
- createPageWithRecording({spaceId, parentPageId?, title?, base64,
  filename, mimeType}): validate/decode the audio first (so a bad payload
  leaves no junk page), resolve the space slug via getSpaceById (no-space
  probe), createPage(), navigate via the router (no reload), wait for the
  new page's editor to be mounted+editable+Yjs-connected, then run the same
  uploadAudioAction path as insertRecording. Resolve-only error contract:
  no-space | create-failed | editor-timeout | insert-failed.

DRY: extract the base64 decode/validate + audio-insert pipeline from
page-editor.tsx into features/editor/gitmost/gitmost-recording.ts; the
existing insertRecording now delegates to it (behavior unchanged).

Mount GitmostGlobalBridge once in GlobalAppShell. Before navigating, reset
the shared yjsConnectionStatusAtom so the readiness gate waits for the NEW
page's provider to connect instead of a stale "connected" from a previously
open page.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/client/src/components/layouts/global/global-app-shell.tsx

@@ -14,6 +14,7 @@ import { SpaceSidebar } from "@/features/space/components/sidebar/space-sidebar.
 import { AppHeader } from "@/components/layouts/global/app-header.tsx";
 import Aside from "@/components/layouts/global/aside.tsx";
 import AiChatWindow from "@/features/ai-chat/components/ai-chat-window.tsx";
+import GitmostGlobalBridge from "@/features/editor/gitmost/gitmost-global-bridge.tsx";
 import classes from "./app-shell.module.css";
 import { useToggleSidebar } from "@/components/layouts/global/hooks/hooks/use-toggle-sidebar.ts";
 import GlobalSidebar from "@/components/layouts/global/global-sidebar.tsx";
@@ -157,6 +158,10 @@ export default function GlobalAppShell({
     {/* Floating AI chat window. Mounted once globally; it is position: fixed
         and self-hides when closed, so its place in the tree is not critical. */}
     <AiChatWindow />
+      {/* Global gitmost native bridge: registers listSpaces / listPages /
+          createPageWithRecording on window.gitmost so the native host can
+          create a page with a recording even when no page editor is open. */}
+      <GitmostGlobalBridge />
     </>
   );
 }