* test(e2e): live-model scenarios for node-hosted MCP tools and skills
Adds --live to the node-plugin pond E2E: three real Anthropic
(claude-sonnet-4-6) agent turns prove the model can (1) call a node-hosted
MCP tool with a proof token verified in the MCP server's call log, (2) use
a node-published skill from its context, and (3) disambiguate identically
named tools from two nodes via deterministic node-prefixed names. Requires
ANTHROPIC_API_KEY; mock mode unchanged.
* style: explicit sort compare in pond tool-id assertion