feat: adapt to DSH 0.1.2-alpha.1 (Remote gateway + token auth + MarkdownText labels)

Dual-version compatibility: the plugin now works identically on
0.1.0-rc.8 ~ 0.1.1-rc.2 and 0.1.2-alpha.1 (the latter verified against a
source build of the dsh-v0.1.2-alpha.1 tag: mount smoke 14/14 + aggregate
double-mount; 0.1.1-rc.2 re-verified 14/14).

- MarkdownText: alpha.1 renamed the flat optional `codeLabels` prop to a
  required nested `labels: { code: {copyLabel, copiedLabel}, footnotes }`;
  the old prop alone crashes fence rendering with "reading 'code'". All
  four render sites (mermaid / MarkdownHtml / TextEditor / SideChatView)
  now go through src/client/markdown-labels.tsx (dual-shape object passed
  under both prop names).
- e2e mount lanes speak both host dialects (tests/e2e/host-protocol.ts +
  host.ts, unit-locked by tests/e2e-host-protocol.spec.ts):
  - one-time-token browser auth: the launch URL grep extends past the
    `/?token=` query (truncating at `/` loses the token), goto navigates
    the token URL (browser cookie exchange), and stamped navigations
    pre-seed the context cookie via addCookies — the exchange 303 drops
    sibling query params;
  - Remote gateway: dot endpoints first, slash endpoints on 404 fallback,
    with args keyed by the controller parameter name (workspace/create ->
    {request}, session/list -> {_request}; verified on a live host).
- package.json: drop the @deepseek-ai/dsh-client-runtime peer (package
  removed upstream in alpha.1; zero references in the source — the chunk
  externals entry stays and is resolution-tolerant).
- scripts/e2e-mount.sh: fix a latent set -u crash in the npx fallback
  branch ($DSH_CMD followed by a full-width comma parsed as part of the
  variable name).
- CI pin stays at @deepseek-ai/dsh@0.1.1-rc.2 until alpha.1 publishes to
  npm (comment updated); README/AGENTS document the new contracts.
- Version lockstep bumped to 0.17.1.

tests/e2e/toggle-layout.e2e.ts

@@ -17,12 +17,8 @@
 import { mkdirSync, writeFileSync } from 'node:fs'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
-import { test, expect, request, type APIRequestContext } from '@playwright/test'
-
-const BASE_URL = process.env.DSH_E2E_URL
-if (!BASE_URL) {
-  throw new Error('DSH_E2E_URL is not set — boot a DSH web instance with the plugin mounted and point this lane at it (see scripts/e2e-mount.sh)')
-}
+import { test, expect, type APIRequestContext } from '@playwright/test'
+import { PAGE_URL, createHostApi, hostRpc } from './host'
 
 const WORKSPACE_PATH = process.env.DSH_E2E_TOGGLE_WORKSPACE ?? join(tmpdir(), 'dsh-e2e-toggle-workspace')
 
@@ -31,23 +27,12 @@ let api: APIRequestContext
 async function seedSession(): Promise<void> {
   mkdirSync(WORKSPACE_PATH, { recursive: true })
   writeFileSync(join(WORKSPACE_PATH, 'seed.txt'), 'toggle lane\n')
-  const workspace = await api.post(`${BASE_URL}/api/workspace.create`, {
-    data: { type: 'client-request', rpcId: 'e2e-toggle-workspace', method: 'workspace.create', payload: { path: WORKSPACE_PATH } },
-  })
-  expect(workspace.ok(), `workspace.create: ${workspace.status()} ${await workspace.text()}`).toBe(true)
-  const workspaceBody = (await workspace.json()) as {
-    result: { ok: true; value: { workspace: { workspaceId: string } } } | { ok: false; error: unknown }
-  }
-  expect(workspaceBody.result.ok).toBe(true)
-  const workspaceId = (workspaceBody.result as { value: { workspace: { workspaceId: string } } }).value.workspace.workspaceId
-  const session = await api.post(`${BASE_URL}/api/session.create`, {
-    data: { type: 'client-request', rpcId: 'e2e-toggle-session', method: 'session.create', payload: { workspaceId } },
-  })
-  expect(session.ok(), `session.create: ${session.status()} ${await session.text()}`).toBe(true)
+  const workspace = await hostRpc<{ workspace: { workspaceId: string } }>(api, 'workspace.create', { path: WORKSPACE_PATH })
+  await hostRpc(api, 'session.create', { workspaceId: workspace.value.workspace.workspaceId })
 }
 
 test.beforeAll(async () => {
-  api = await request.newContext({ baseURL: BASE_URL })
+  api = await createHostApi()
   await seedSession()
 })
 
@@ -64,7 +49,7 @@ interface FrameSample {
 }
 
 test('bottom panel tracks the center column during the right-panel toggle transition (issue #315)', async ({ page }) => {
-  await page.goto(BASE_URL, { waitUntil: 'domcontentloaded' })
+  await page.goto(PAGE_URL, { waitUntil: 'domcontentloaded' })
   await expect(page.locator('#root > *')).not.toHaveCount(0, { timeout: 90_000 })
   const sidebar = page.locator('[data-dsh-better-sidebar]')
   await expect(sidebar).toBeAttached({ timeout: 90_000 })