fix: review-bot findings on the provider-hosted shell

- Keep ConversationSession mounted for blank sessions (chrome-less) so the
  draft-persistence mirror stays bound in the hero; hero typing reaches the
  chat store again.
- Restore the baselines-ready gate in AppFrame: empty boot snapshots no
  longer flash the New Workspace hero before either baseline lands.
- Commit ordinary sends through the machine (send-committed event +
  Shell.commitSend): undo can no longer resurrect already-sent content on
  the default-sink path.
- Give the production InputMachine a real wall clock so the typing-run
  merge window actually expires.
- Coalesce concurrent connectWorkspace creates per workspace: the summary
  has no cwd until the host frame lands, so a second New Session inside
  that window minted a duplicate hidden blank session.

packages/client/ui-layout/tests/app-frame.spec.tsx

@@ -160,13 +160,11 @@ describe('AppFrame', () => {
     expect(slotCalls.map((c) => c.key)).toContain('conversation')
   })
 
-  it('renders both column occupants before baselines settle (no loading gate)', () => {
-    // The loading branch is gone: fixed tree positions from first paint, the
-    // occupants render their own pending states.
+  it('keeps the loading branch until both object-layer baselines are ready', () => {
     baselinesReady.current = false
-    const { slotCalls } = mountFrame()
-    expect(slotCalls.map((c) => c.key)).toContain('conversation')
-    expect(slotCalls.map((c) => c.key)).toContain('details')
+    const { slotCalls, getByRole } = mountFrame()
+    expect(getByRole('status').textContent).toContain('Loading workspaces and sessions')
+    expect(slotCalls.map((c) => c.key)).not.toContain('conversation')
   })
 
   it('sidebar slot receives live concession output as owner props', () => {