fix(gui): keep sidebar controls when collapsed

A closed sidebar previously resolved to a zero-width grid track, clipping
the only toggle and the settings entry with no visible recovery; the closed
preference persisted across reloads, locking the sidebar shut.

- columns.ts maps the closed preference (width 0) to a fixed 60px
  SIDEBAR_COLLAPSED rail through every step of the concession solve;
  closed details still resolve to zero width.
- AppFrame derives data-sidebar-collapsed and the sidebar slot's collapsed
  owner prop from the persisted preference instead of the resolved track
  width, and drops the resize handle while collapsed.
- SidebarRoot reads the owner collapsed prop; the expanded-only body is a
  separate component that unmounts while collapsed (dropping its sessions
  subscription), leaving the expand toggle and Settings in the rail.
- The keyless web smoke gains the ui-sidebar bundle (six real bundles) and
  pins the 60px rail collapse/expand round through the assembled client.

apps/web/tests/smoke-fixture.e2e.ts

@@ -1,9 +1,9 @@
 // Keyless boot-chain smoke over the REAL carrier: startWebServer + web-plugins
 // registry surface + __DSH_BOOT__ injection + built shell dist in a real
 // chromium. First describe: manifest injection + fail-loud half. Second
-// describe: the settled success pass — five REAL tsdown bundles (the
-// infrastructure four + layout) load through the DI chain in ?fixture mode
-// and the three-column frame appears in one flip. The full conversation
+// describe: the settled success pass — six REAL tsdown bundles (the
+// infrastructure four + layout/sidebar) load through the DI chain in ?fixture
+// mode and the three-column frame appears in one flip. The full conversation
 // round lands in smoke-real under the W5 real-host standard.
 import { existsSync } from 'node:fs'
 import { fileURLToPath } from 'node:url'
@@ -17,13 +17,14 @@ import { DIST_INDEX, probeFreePort, requireDist, saveFailureShot } from './suppo
 const bundlePath = (dir: string): string =>
   fileURLToPath(new URL(`../../../packages/client/${dir}/lib/client.js`, import.meta.url))
 
-/** id ↔ bundle table for the success pass (immediately four + layout). */
+/** id ↔ bundle table for the success pass (immediately four + layout/sidebar). */
 const REAL_PLUGINS: { id: string; dir: string; inject: string[]; immediately?: boolean }[] = [
   { id: '@deepseek-ai/dsh-client-connection', dir: 'connection', inject: [], immediately: true },
   { id: '@deepseek-ai/dsh-client-runtime', dir: 'runtime', inject: ['@deepseek-ai/dsh-client-connection'], immediately: true },
   { id: '@deepseek-ai/dsh-client-ui-theme', dir: 'ui-theme', inject: [], immediately: true },
   { id: '@deepseek-ai/dsh-client-i18n', dir: 'i18n', inject: [], immediately: true },
   { id: '@deepseek-ai/dsh-client-ui-layout', dir: 'ui-layout', inject: ['@deepseek-ai/dsh-client-runtime'] },
+  { id: '@deepseek-ai/dsh-client-ui-sidebar', dir: 'ui-sidebar', inject: ['@deepseek-ai/dsh-client-ui-layout'] },
 ]
 
 /** Manifest served by the fake registry: one live bundle row, one missing row. */
@@ -91,7 +92,7 @@ describe('web boot chain (keyless, real carrier)', () => {
   })
 })
 
-describe('web boot chain success pass (keyless, five real bundles, ?fixture)', () => {
+describe('web boot chain success pass (keyless, six real bundles, ?fixture)', () => {
   const missing = REAL_PLUGINS.filter(p => !existsSync(bundlePath(p.dir)))
   let server: Awaited<ReturnType<typeof startWebServer>>
   let browser: Browser
@@ -141,6 +142,21 @@ describe('web boot chain success pass (keyless, five real bundles, ?fixture)', (
     const owners = await page.evaluate(() =>
       [...document.querySelectorAll('style[data-plugin]')].map(s => (s as HTMLElement).dataset['plugin']))
     expect(owners).toContain('@deepseek-ai/dsh-client-ui-layout')
+    expect(owners).toContain('@deepseek-ai/dsh-client-ui-sidebar')
+  })
+
+  it('collapsed sidebar keeps a 60px rail with expand and settings controls', async () => {
+    onTestFailed(() => saveFailureShot(page, 'smoke-boot-collapsed-rail'))
+    const frame = page.locator('[class*="frame"]')
+    const firstTrack = async (): Promise<string> => (await frame.evaluate(
+      el => getComputedStyle(el).gridTemplateColumns)).split(' ')[0]!
+    await page.getByRole('button', { name: 'Collapse sidebar' }).click()
+    expect(await firstTrack()).toBe('60px')
+    await expect(page.getByRole('button', { name: 'Expand sidebar' }).isVisible()).resolves.toBe(true)
+    await expect(page.getByRole('button', { name: 'Settings' }).isVisible()).resolves.toBe(true)
+    await page.getByRole('button', { name: 'Expand sidebar' }).click()
+    expect(await firstTrack()).toBe('300px')
+    await expect(page.getByRole('button', { name: 'Collapse sidebar' }).isVisible()).resolves.toBe(true)
   })
 
   it('stayed clean: no page errors across the whole load chain', () => {