fix: mcp page results shows non mcp tools

[prncexe]

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Summary

Fixes #36647. The MCP page's filter logic in web/app/components/tools/mcp/index.tsx had a bug where the collection.type === 'mcp' check was only applied when searchText was empty. When a search term was entered, the filter returned any tool whose name matched, regardless of type — causing non-MCP tools (e.g., built-in tools) to appear in the MCP results. This fix extracts isMcpType into a shared variable so the type constraint is always enforced, even during search.

Screenshots

Before	After
Searching shows non-MCP tools mixed in results	Only MCP-type tools match when searching

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

[fatelei]

web style check failed