feat: add optional You.com search integration

[mouse-value-add]

Summary

Adds You.com web search and research capabilities to ECA via MCP server configuration examples. This enables ECA users to add web search, URL content extraction, and AI-powered research tools to their coding agents across all supported editors (VSCode, Emacs, Vim, IntelliJ, Desktop).

What Changed

Added comprehensive You.com MCP server examples to docs/config/tools.md:

• Authenticated access: Full features using YDC_API_KEY environment variable
• Keyless option: Basic web search using the free profile (?profile=free)
• Specialized profiles: Finance-only and docs-only endpoints for focused use cases

Integration Approach

This follows ECA's existing MCP server patterns and requires zero code changes — purely additive configuration examples. The integration leverages ECA's built-in support for:

• HTTP MCP servers with authentication headers
• Environment variable interpolation for API keys
• Multiple server configurations

Available Tools

Once configured, users gain access to:

• you_search — Web search with citations
• you_url_contents — Webpage content extraction
• you_research — Multi-step research workflows

Configuration Examples

Basic authenticated setup:

{
  "mcpServers": {
    "you-search": {
      "url": "https://api.you.com/mcp",
      "headers": {
        "Authorization": "Bearer ${env:YDC_API_KEY}"
      }
    }
  }
}

Keyless trial:

{
  "mcpServers": {
    "you-search-free": {
      "url": "https://api.you.com/mcp?profile=free"
    }
  }
}

Validation

• Follows ECA's established documentation patterns
• Uses existing MCP server configuration system
• No breaking changes or code modifications
• Maintains ECA's security model (opt-in via configuration)
• Includes proper UTM tracking for attribution

Tracking issue: youdotcom-oss/integration-tracking#202

[ericdallo]

nice, since this is docs only I'm ok with that, thank you!