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/workspace/workspace/src/index.ts

@@ -139,6 +139,11 @@ export class WorkspaceRegistry extends Service {
    * @param title - Display title used only when a new record is created.
    * @returns the existing or newly durable workspace.
    */
+  // TODO: `title` lost its last production caller when the gateway's
+  // create-by-name branch was deleted
+  // (.agents/notes/implemented/simplification/2026-07-31-one-route-to-add-a-workspace.md);
+  // drop the parameter with its @param clause and the `create(path, title?)`
+  // lines in this package's README pair.
   async create(path: string, title?: string): Promise<Workspace> {
     const canonical = await realpathNormalize(path)
     if (!(await stat(canonical)).isDirectory()) {