fix(mcp): keep facade tools available after late connections

[luoye520ww]

Summary

Partial implementation for the rejected KunAgent#697 replacement.

Problem

In MCP search mode, late-connected servers from OAuth/background reconnect can gain resources/prompts capabilities after startup. A startup-only provider registration path can miss those capabilities.

Changes implemented

• Extended McpClientLike with optional resources/prompts methods:
  • listResources
  • readResource
  • listResourceTemplates
  • listPrompts
  • getPrompt
• Added conservative resource/template/prompt descriptor types.
• Updated the SDK transport wrapper to forward those optional SDK methods when present.
• Added kun/src/adapters/tool/mcp-facade-provider.ts, a stable facade provider that exposes:
  • mcp_list_resources
  • mcp_read_resource
  • mcp_list_resource_templates
  • mcp_list_prompts
  • mcp_get_prompt
• Removed the non-code .kun/review-plans file from this PR scope.

Still required before this PR is reviewable

• Wire createMcpFacadeProvider(connected) into mcp-tool-provider.ts regardless of searchActive.
• Ensure advertisedToolCount is computed after adding the facade provider.
• Add tests for search-mode startup, OAuth late connect, background reconnect, and no direct-provider duplication.

Validation to run locally

npm --prefix kun run typecheck
npm --prefix kun test

I could not run local commands from this environment, so this remains draft.