fix(skills): propagate module semantic failures

[CloudTianTian]

Summary

• treat a module Skill result with top-level ok: false as a semantic failure
• preserve the structured JSON report on stdout while returning exit code 1
• keep module-specific fields such as valid: false informational unless ok is explicitly false

Validation

• npm run test:js -- test/main/util/run-skill.test.ts (13 passed, 2 unrelated platform cases skipped)
• npm run typecheck
• git diff --check
• Orkas sync precheck: private docs and eval coverage excluded; shared runner and deterministic regression coverage retained

Source fix: Orkas commit 76511973d1380e501e29138f7f4097c1234778f0