[codex] fix Self-Harness runtime utilities

[tractorjuice]

Summary

• Make the Self-Harness tracer ESM-safe and expose testable JSON input processing.
• Make harness validation reject missing scored results instead of fabricating random scores.
• Keep weakness-miner cluster frequencies numeric after repeated failures.
• Apply tool restriction/add/disable proposals correctly for object-shaped MCP configs.
• Add focused Node tests covering the PR [codex] add Self-Harness autoresearch implementation #606 review regressions.

Validation

• node --check plugins/arckit-claude/hooks/autoresearch-tracer.mjs && node --check plugins/arckit-claude/hooks/harness-proposer.mjs && node --check plugins/arckit-claude/hooks/harness-validator.mjs && node --check plugins/arckit-claude/hooks/weakness-miner.mjs && node --check tests/plugin/self-harness.test.mjs
• node --test tests/plugin/self-harness.test.mjs
• git diff --check HEAD~1 HEAD