docs(pages): add MCP Server docs section

[YinkaMetrics]

Description

Adds the missing MCP Server section to the Docs page, placed after ocr viewer, with CLI configuration commands, supported field descriptions, the conflict/timeout note, and a CodeGraph example. Also adds the required docs sidebar/title/content keys for English, Chinese, and Japanese.

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)
• Refactoring (no functional changes)
• Documentation update
• CI / Build / Tooling

How Has This Been Tested?

• make test passes locally
• Manual testing (describe below)

Manual validation:

• cd pages && npm run typecheck
• cd pages && npm run build

npm run build passes with existing webpack bundle-size warnings.

Checklist

• My code follows the project's coding style (go fmt, go vet)
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or my feature works
• New and existing unit tests pass locally with my changes
• I have updated the documentation accordingly (if applicable)
• I have signed the CLA

Related Issues

Closes #259

[CLAassistant]

All committers have signed the CLA.

[github-actions]

✅ OpenCodeReview: No comments generated. Looks good to me.