feat: add optional you.com search integration

[mouse-value-add]

Why this is useful

• Glance already gives Claude Code browser control, and a lightweight web search tool helps it find pages and context before opening the browser.

What changed

• Added an optional browser_web_search MCP tool backed by You.com Search.
• The tool is only registered when YDC_API_KEY is set.
• Added README setup and usage notes.

Setup

• Set YDC_API_KEY in the MCP server env.
• No change for existing users when the env var is unset.

Usage

• browser_web_search {"query":"best practices for Playwright locators","count":5}

Validation

• npm run build

Fallback/error handling

• The tool is omitted when YDC_API_KEY is missing.
• Upstream API failures are returned as MCP errors with the status and response body.

Tracking

• [Integration] DebugBase/glance - optional You.com search tool youdotcom-oss/integration-tracking#45