Make the Engineering Harness adaptive and stack-neutral

[Mrbaeksang]

Summary

• make assistive the default: natural confirmations, no task IDs/hashes/lease ceremony for normal work
• replace framework/DDD bias with repository-first and current official-source stack research
• add task-size routing, compact specs, tracer-bullet slices, implementation, and on-demand artifact guidance
• keep the original scoped-lease lifecycle as explicit strict compatibility mode
• add a thin Codex safety adapter that allows normal and specialized tools while protecting secrets, Harness/provider files, root escapes, and the provider canary
• publish the behavioral change as 0.2.0

Verification

• npm test — PASS (195 Python tests, 7 environment skips; 3 npm tests)
• npm run verify:distribution — PASS
• git diff --check — PASS
• trusted provider-canary and audit fixtures — PASS

Live canary note

A fresh temporary Project could not complete the real Codex canary because that new Project Hook had not received user trust. No trust state was forged; the temporary fixture was moved to Trash.