Restore Critic verify-by-temporary-test workflow

[TheGreatAxios]

Summary

• Restores the verify-by-temporary-test workflow in the Critic prompt: form hypotheses, write temp tests under tmp/critique-tests, run them, report only verified issues, recommend keepers for permanent inclusion
• Keeps the existing API-contract check, this-diff hygiene, and never-fix rules intact; the shared scaffold still owns the report envelope

Verification

• bun run typecheck, bun run build, and bun run test pass
• bun run check passes: 7133 pass, 0 fail
• Critic contract tests cover the temp-test workflow and the no-envelope rule

Fixes CL-7655

[linear-code]

CL-7655