v2.9.0 — MCP 2.0 protocol + server-side aggregation

• Migrated to the MCP 2.0 (2026-07-28) protocol on the official SDK — backward-compatible with existing clients.
• Server-side aggregation: multi-day pulls now return a totals block so answers use GA4-computed period figures directly.
• Smarter setup recovery: on clients that support it, missing configuration is collected right where a query fails.
• Richer, privacy-preserving diagnostics to keep improving the tool.