test(sdk): snapshot suite over the SDK path; docs for the SDK stack

- examples/jsonrpc-agent gains its first snapshot suite (sdk.snapshot.ts):
  the real dsh-jsonrpc-agent runtime driven through the real dsh-sdk-client,
  keyless llm-replay behind a new cordis.snapshot.yml overlay; three recorded
  scenarios (text turn, bash tool, spawn subagent) pin the notification
  stream, the SDK turn result, and the persisted parent+child session logs.
- Bilingual READMEs for dsh-sdk-protocol / dsh-sdk-client / dsh-subagent-sdk;
  sdk/ and subagent/ group tables extended; dsh-jsonrpc README points at the
  extracted protocol package; Agent Note (en+zh) owns the decision.
- The proposed make-jsonrpc-directional note is updated for the transport's
  new home and its second (client) consumer.
- Model Experience sentence allowlist entries for the two client-side
  packages; module graph + config catalog regenerated; i18n pairings
  recorded. doc-sync passes 24/24.

pnpm-lock.yaml

@@ -484,6 +484,9 @@ importers:
       '@deepseek-ai/dsh-subagent-fork':
         specifier: workspace:*
         version: link:../packages/subagent/subagent-fork
+      '@deepseek-ai/dsh-subagent-sdk':
+        specifier: workspace:*
+        version: link:../packages/subagent/subagent-sdk
       '@deepseek-ai/dsh-subagent-spawn':
         specifier: workspace:*
         version: link:../packages/subagent/subagent-spawn