fix(code-runtime-python): satisfy static gates for the protocol-only layer

- Drop the unused @deepseek-ai/dsh-code-runtime dependency: this layer
  imports nothing from the seam (protocol.ts has no imports; the invariant
  companion uses only cordis and dsh-invariants). The backend-core PR
  re-adds it when PythonCodeRuntime consumes the seam. Fixes knip.
- Point the Agent Note's cross-reference to the seam note at the English
  target on both language sides, per the bilingual-pairing contract (only
  the language switcher flips to .zh.md). Re-record the sidecar.
- Add the Known Limitations section both READMEs require, covering the
  cross-language guard's scope and the deferred runtime implementation.
- Regenerate the module graph for the dropped dependency edge.

packages/code-runtime/code-runtime-python/package.json

@@ -27,12 +27,10 @@
   ],
   "license": "BSD-3-Clause",
   "peerDependencies": {
-    "@deepseek-ai/dsh-code-runtime": "^0.0.1",
     "@deepseek-ai/dsh-invariants": "^0.0.1",
     "cordis": "^4.0.0-rc.7"
   },
   "devDependencies": {
-    "@deepseek-ai/dsh-code-runtime": "workspace:^",
     "@deepseek-ai/dsh-invariants": "workspace:^",
     "cordis": "^4.0.0-rc.7"
   }