Fix CLI web search/fetch command SecretRef resolution for provider-scoped plugin credentials.
- Carry command provider overrides through gateway and local secret resolution.
- Mark the selected web provider targets active and unrelated plugin refs inactive.
- Cover Tavily, DuckDuckGo, legacy Firecrawl fetch, protocol overrides, and runtime command-secret behavior.
- Add public plugin-sdk test mock exports needed by existing plugin tests after CI boundary enforcement.
Fixes#82621.
Replacement for #82699.
Co-authored-by: 吴杨帆 <39647285+leno23@users.noreply.github.com>
