Harden managed test preparation and run diagnostics

[jamil2018]

Summary

• fail fast on stale or unresolved managed preparation bindings before durable lifecycle mutation, with compact hash-bound preflight receipts
• preserve canonical built-in operation identity while allowing optional node labels to drive Gherkin and run-log presentation
• emit distinct generated Cucumber registration lines and include bounded visible form-validation messages in browser failures
• repair coordinator not-found handling, target-owned locator discovery, runtime Step Reference compatibility, and runtime-safe managed IDs found during the Shopify planning run
• sync create-appraisejs templates and Graphify outputs

Validation

• 715 unit tests
• 40 Playwright E2E tests
• production build
• appraisejs MCP contract tests
• create-appraisejs package tests
• Fallow commit gate
• React Doctor 99/100 (one existing progressive-enhancement warning)
• harness, generated-artifact, and package-content checks