refactor(jobs,terminal): import HarnessError from dsh-error

JobError and TerminalError only need the error base, so dsh-jobs and
dsh-terminal depend on dsh-error instead of the LLM runtime. The Python
SDK runtime closure includes the new package.

Refs #7869

python/sdk-runtime/package.json

@@ -46,6 +46,7 @@
     "@deepseek-ai/dsh-credentials": "workspace:*",
     "@deepseek-ai/dsh-deepseek-account": "workspace:*",
     "@deepseek-ai/dsh-deepseek-llm-api-extensions": "workspace:*",
+    "@deepseek-ai/dsh-error": "workspace:*",
     "@deepseek-ai/dsh-file-reference": "workspace:*",
     "@deepseek-ai/dsh-fs": "workspace:*",
     "@deepseek-ai/dsh-fs-local": "workspace:*",