feat(mcp): query Google Cloud metrics live with PromQL - #1478

🟢 Confidence 7/10 · likely safe to merge
The tools are contained and tested, but the two open rendering defects are still in the head's chat path.
_{quality 88/100 · 1 warning · 1 note · tests covered · risk medium · 2/2 new units observable}

Adds two public MCP tools that read Google Cloud Monitoring live over Google's PromQL API, their output schemas, chart/table rendering and the ai Worker's Google key binding. Safe to merge once the two open chat-rendering issues are fixed.

• query_gcp_promql and find_gcp_metrics register as public read-only MCP tools
• Range results draw through promQlChartRows; instant results as a table
• The ai Worker binds MAPLE_GCP_SERVICE_ACCOUNT_KEY and GcpPromQlService joins the MCP runtime

Before merge

• Secret · Add MAPLE_GCP_SERVICE_ACCOUNT_KEY to the ai app's prd and dev secret stores; without it both tools answer unavailable · apps/ai/src/worker.ts:68

Still open from earlier reviews

• 🟠 Warning · F1 · Chat instant table shows the oldest point, not the value at end_time · apps/web/src/components/ai-elements/renderers/tool-renderer.tsx:192
• 🔵 Note · F2 · seriesKey collides two series whose label values contain , or = · apps/web/src/components/ai-elements/renderers/components/promql-chart-rows.ts:8

Production impact

_{7bccd6c · Updated on every push. Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}