Add Google Analytics support to the common MCP server

[bensenescu]

Problem

Users can access Search Console through the OpenSEO MCP server and want GA4/Google Analytics available in the same agent workflow.

Evidence

• User feedback: "you have already implemented search console for MCP, do you plan anything for google analytics as well to fetch items at one go from your common mcp server?"

Suggested direction

Write a short spec for adding GA4 read-only MCP tools, starting with SEO-relevant analytics rather than a generic GA dashboard.

Clarify:

• OAuth scope and setup path, likely analytics.readonly.
• Initial tool surface: properties, organic landing pages, page performance, conversions, ecommerce if relevant.
• How GA4 data should combine with Search Console data for opportunity scoring.
• Non-goals for v1, especially GA4 admin/write actions.

Acceptance criteria

• Spec defines the initial GA4 MCP tool set and required OAuth scopes.
• Spec explains how setup differs from Search Console.
• Spec identifies SEO-specific combined workflows worth building first.
• Spec calls out test/fixture needs and non-goals.