fix(mcp): align GSC setup response schema

[CooperSheroy]

Summary

Fixes the self-hosted Google Search Console setup response so its structuredContent matches the declared MCP output schema. The setup response already carries ok: false, reason: "gsc_oauth_not_configured", and setupDocsUrl, so the undeclared connected field is removed.

This PR is AI-assisted and focused as a proof-of-concept fix.

Related Issues

Fixes #261

Changes

• Remove the undeclared connected property from the shared self-hosted GSC setup MCP response.
• Add schema-validation assertions for the self-hosted setup path on both get_search_console_performance and inspect_urls, since both use the same response helper.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactoring (no functional changes)
• CI/CD or build changes

Verification

Steps to reproduce / test

1. pnpm install --frozen-lockfile
2. pnpm vitest run src/server/mcp/tools/search-console-tools.test.ts
3. pnpm exec prettier --check src/server/mcp/tools/search-console-tools.ts src/server/mcp/tools/search-console-tools.test.ts
4. git diff --check

What you personally verified

• The focused Search Console MCP tool test file passes: 10 tests passed.
• The self-hosted setup response for get_search_console_performance validates against that tool's declared output schema.
• The same shared setup response also validates against inspect_urls output schema.
• Formatting and whitespace checks pass.

Evidence

• CI passes (pnpm check && pnpm lint && npx tsc --noEmit)
• Manually tested locally
• Screenshots / recordings attached (if UI changes)

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have added/updated documentation as needed
• My changes do not introduce new warnings