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/smoke-real.e2e.ts

@@ -20,7 +20,7 @@ import { createServer } from 'node:http'
 import { createRequire } from 'node:module'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
-import { pathToFileURL } from 'node:url'
+import { fileURLToPath, pathToFileURL } from 'node:url'
 import type { Browser, Page } from 'playwright'
 import { chromium } from 'playwright'
 import { afterAll, beforeAll, describe, expect, it, onTestFailed } from 'vitest'
@@ -455,7 +455,12 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY || notReady.length > 0)('web smoke
     const tsxLoader = pathToFileURL(createRequire(join(REPO_ROOT, 'package.json')).resolve('tsx')).href
     child = spawn(
       process.execPath,
-      ['--import', tsxLoader, join(REPO_ROOT, 'apps/cli/src/bin.ts'), 'web', '--port', String(port)],
+      [
+        '--import', tsxLoader, join(REPO_ROOT, 'apps/cli/src/bin.ts'), 'web', '--port', String(port),
+        // Pin the in-browser picker: the shipped `-auto` row would resolve to
+        // the native OS chooser on this bind, and no page can drive that.
+        '--config', fileURLToPath(new URL('./pin-browse-picker.overlay.yml', import.meta.url)),
+      ],
       {
         cwd: sessionsDir,
         env: {
@@ -496,7 +501,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY || notReady.length > 0)('web smoke
   it('2+3 empty-state first send completes a real model round', async () => {
     onTestFailed(() => saveFailureShot(page, 'w5-first-round'))
     // Fresh world: connect a Workspace so the composer starts live.
-    await connectFreshWorkspace(page)
+    await connectFreshWorkspace(page, sessionsDir)
     const input = page.locator('textarea').first()
     await input.waitFor({ timeout: 10_000 })
     await screen(page, '02-empty-state')