fix(web): address the review round on the one-route add flow

- lifecycle-chrome's second scaffold staged its workspace under the OUTER
  scaffold's temp root, coupling two supposedly independent worlds and
  leaving the aria scrub root wrong; it now uses its own workspaceCwd.
- The direct-open path now carries the same `flowBusy` gate that disables
  the equivalent menu entry, so an occupant re-registering mid-adoption
  cannot raise a second flow.
- A composition with no directory-picker no longer opens a zero-entry
  popover on the hero anchor: with nothing to pick and nothing to add,
  the gesture shows nothing. Both behaviors gain a unit test.
- Brought three partially superseded Agent Notes current (the native
  picker, the workspace UI product flow, and the sidebar browsing split),
  cross-linked to this decision, both languages re-recorded.
- Corrected this Note's own Testing section: the shared e2e helper stages
  and adopts its directory, it does not create one in-dialog — only
  workspace-management does. Named the client-seam and CLI-README residue
  in the follow-up TODO alongside the wire branch.

apps/web/tests/lifecycle-chrome.e2e.ts

@@ -93,7 +93,7 @@ describe('web e2e: lifecycle & chrome (workspace flow / reload / dark mode)', ()
     try {
       await activePage.goto(activeScaffold.baseUrl, { waitUntil: 'load' })
       await activePage.waitForSelector('[class*="frame"]', { timeout: 30_000 })
-      await connectFreshWorkspace(activePage, scaffold.workspaceCwd)
+      await connectFreshWorkspace(activePage, activeScaffold.workspaceCwd)
       const input = activePage.locator('textarea').first()
       await activePage.getByRole('button', { name: 'Commands' }).click()
       const menu = activePage.getByRole('listbox', { name: 'Trigger suggestions' })