cleanup(web): give adding a Workspace one route

Both Workspace surfaces offered "Open local folder…" and "Create a new
workspace" for one outcome. The browse occupant already carries its own
New folder affordance, so picking a directory covered creating one; the
name dialog only added a second vocabulary and a create target the
operator could neither see nor choose.

The surviving entry is named after the outcome — "Add workspace…" — and a
menu now appears only where there is something to choose between: with no
Workspace listed (the add-only sidebar header, or an empty hero list) the
anchor gesture raises the directory flow directly instead of a one-row
popover. An empty list counts as final only after the list baseline lands,
and a composition with no directory-flow occupant hides the sidebar button
rather than offering a dead one.

WorkspaceCreateFlow becomes WorkspacePickFlow (createOnly -> addOnly) and
the injected createWorkspace narrows to { path }. The host's
workspace.create({ name }) branch and `dsh web --workspace-root` lost their
last product consumer; both are marked at the call site for a follow-up.

apps/web/tests/access-confirmation.e2e.ts

@@ -2,6 +2,7 @@
 // the same locale-aware, in-page risk confirmation. Zero model calls: the
 // scenario boots the shipped Web composition and exercises the real
 // permission projection, client command path, HTTP RPC, and pushed update.
+import { mkdirSync } from 'node:fs'
 import { fileURLToPath } from 'node:url'
 import { join } from 'node:path'
 import type { Browser, Page } from 'playwright'
@@ -19,13 +20,16 @@ import { saveFailureShot } from './support.ts'
  * boots; this scenario deliberately keeps zh, so the localized picker
  * copy is the anchor set).
  */
-async function connectFreshWorkspaceZh(page: Page, name = 'workspace'): Promise<void> {
+async function connectFreshWorkspaceZh(page: Page, root: string, name = 'workspace'): Promise<void> {
+  mkdirSync(join(root, name), { recursive: true })
   await page.getByRole('button', { name: '选择工作区' }).click()
-  await page.getByRole('menuitem', { name: '新建工作区' }).click()
-  const dialog = page.getByRole('dialog', { name: '新建工作区' })
+  const dialog = page.getByRole('dialog', { name: '选择工作区目录' })
   await dialog.waitFor({ timeout: 10_000 })
-  await dialog.getByLabel('新工作区名称').fill(name)
-  await dialog.getByRole('button', { name: '创建工作区' }).click()
+  await dialog.getByRole('button', { name: '编辑路径' }).click()
+  const pathInput = dialog.getByRole('textbox', { name: '编辑路径' })
+  await pathInput.fill(join(root, name))
+  await pathInput.press('Enter')
+  await dialog.getByRole('button', { name: '打开', exact: true }).click()
   await page.locator('textarea:enabled[placeholder="描述你想要构建的内容"]')
     .waitFor({ timeout: 15_000 })
 }
@@ -53,7 +57,7 @@ describe('web e2e: Full access confirmation', () => {
     tripwire = watchConsole(page)
     await page.goto(scaffold.baseUrl, { waitUntil: 'load' })
     await page.waitForSelector('[class*="frame"]', { timeout: 30_000 })
-    await connectFreshWorkspaceZh(page)
+    await connectFreshWorkspaceZh(page, scaffold.workspaceCwd)
   }, 120_000)
 
   afterAll(async () => {