Add Lumin evidence workflow guardrails

[hun99999]

Summary

• add an evidence-backed Lumin workflow to the setup playbook and vibe-coding guide
• add a structural evidence index for local.md / Obsidian / private wiki usage
• teach apply/start prompts to require scan range, invocation-specific pre-write advisory, and post-write delta review
• report existing .audit artifacts in optional tool inventory without installing or writing anything
• add docs-contract tests for Lumin evidence, canon source limits, and no overclaimed machine outputs

Lumin mapping

• structural claims require machine or direct file evidence
• absence claims require scan range
• pre-write intent tracks names, shapes, files, dependencies, plannedTypeEscapes
• post-write machine evidence is scoped to type escapes, unexpected files, scan/confidence changes
• duplicate helpers, dependency drift, API drift, and re-export drift stay manual review claims
• Lumin canon sources are limited to type ownership, helper registry, topology, naming
• broader boundary/API/dependency/re-export facts belong in living audit or project docs

Verification

• python3 -m unittest discover -s tests -p 'test_*.py' (101 tests)
• python3 scripts/audit_agent_stack.py
• python3 scripts/check_private_paths.py
• git diff --check

Review

• Subagent reviewer found two medium issues around Lumin overclaims and weak tests.
• Follow-up fixes were applied and the reviewer re-checked those findings with no remaining issues.