dogfood: prove explicit LoopSpine trigger selection

[uncfreak1255-code]

Summary

• add an isolated Claude Code trigger/non-trigger smoke for the local plugin path
• verify exact Read events, one-plugin isolation, zero hooks, no MCP servers, and unchanged tracked state
• distinguish explicit LoopSpine receipt behavior from the same plain non-invoked readback
• record the passing run as DF-02 and advance the pilot to 2/10

Proof

• npm test: pass, including 19 Claude access-event cases
• claude plugin validate .: pass
• npm run smoke:trigger-selection: pass, all 12 assertions
• staged autoreview: clean

Boundary

This proves explicit local invocation behavior only. It does not prove automatic selection, global readiness, task-quality improvement, or hook readiness.