feat: add confidence level to status reports in taskMaestro watch

[JeremyDev87]

Purpose

Status reports said "✅ 완료" without showing verification basis. Led to false trust in stale data.

Solution

Every status report must include verification basis:

• "✅ PR #N (RESULT.json validated: issue match + pane idle confirmed)"
• "🔄 WORKING (active spinner: ✽ Implementing… · ↓ 5.3k tokens)"
• "⚠️ UNCERTAIN (RESULT.json exists but pane still active — cross-verify needed)"

Never report bare "✅" without parenthetical evidence.

References

• Incident: Wave B feat: codingbuddy init — project initialization CLI #813 reported complete with stale RESULT.json
• Parent: Improve taskMaestro orchestration reliability (session 2 retrospective) #900

[JeremyDev87]

Implemented in PR #918 (batch update)