docs,test: settle review follow-ups for the create-by-name deletion

Rewrite the three sibling Agent Note pairs that still described create-by-name
as current (workspace-ui-product-flow, session-list-browsing-and-manual-order,
same-basename-workspace-adoption) and the one-route note's own alternative and
section title; delete scripts/hero-composer-dom-continuity.mjs, which drove the
name dialog removed by the one-route change; mark WorkspaceRegistry.create's
now test-only title parameter with a deletion TODO; pin the retired { name }
spelling as a schema rejection; align the workspace spec on stageDir and the
fixture spec title on path creates.

packages/client/connection/tests/fixture.spec.ts

@@ -535,7 +535,7 @@ describe('createFixtureApi', () => {
     expect(reused.result.value).toMatchObject({ created: false, workspace: { workspaceId: 'fx-ws-fixture' } })
   })
 
-  it('workspace.create by name mints a new entity and pushes host/workspace-changed', async () => {
+  it('workspace.create on a fresh path mints a new entity and pushes host/workspace-changed', async () => {
     const api = createFixtureApi()
     const abort = new AbortController()
     const seen: HostFrame[] = []