Add recipe phase diagnostics

[chubes4]

Summary

• Adds structured recipe phaseEvidence for runtime startup, plugin mount, plugin activation, blueprint application, workload execution, and artifact collection.
• Classifies plugin activation failures separately from workload failures and includes plugin-file diagnostics for activation errors.
• Refreshes runtime reference/replay evidence hashes after recipe evidence files are added so strict artifact verification remains valid.

Closes #584.

Testing

• npm run build
• npm run recipe-runtime-evidence-smoke
• npm run recipe-workflow-phases-smoke
• npm run recipe-heavyweight-plugin-runtime-smoke

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Implemented the phase diagnostics and smoke coverage, diagnosed the strict artifact verifier regression exposed during testing, and ran the targeted verification commands. Chris remains responsible for review and acceptance.