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.

src/client/chunk-loader.ts

@@ -67,6 +67,13 @@ type ChunkFactory = (require: (spec: string) => unknown) => ChunkExports
  * (stripClientSuffix). dsh-client-web-react / dsh-client-schema-form were
  * dropped in DSH 0.1.0-rc.8 (no rc.8 publish, nothing requires them) — the
  * chunks never asked for them, so they no longer belong here.
+ *
+ * DSH 0.1.2-alpha.1 removed the `dsh-client-runtime` package outright (the
+ * seed table gained bare-name `@deepseek-ai/dsh-client-store` instead); the
+ * runtime/client row below stays for 0.1.1-rc.x hosts — no chunk requires
+ * it, and {@link buildExternalsRequire} keeps an unresolvable spec
+ * undefined until a chunk actually asks (only then is it a loud error), so
+ * the entry is inert on 0.1.2-alpha.1+.
  */
 export const CHUNK_EXTERNALS: readonly string[] = [
   'react',