Add intent-aware research triage before backlog creation #1650

Parent epic: #1648

Outcome

Add /squad triage between research and planning so findings are classified while the root intent, constraints, and evidence remain available.

Dispositions

Required, prerequisite, defect, security/operational risk, modernization debt, enhancement, optional follow-up, duplicate, out of scope, deferred, or needs human decision.

Acceptance criteria

• Every finding receives exactly one disposition, evidence, confidence, and rationale.
• Triage consumes authoritative intent and research, not generated issue titles alone.
• Out-of-scope/deferred findings remain visible but do not enter the work queue.
• Decision-required findings block only affected plan branches.
• Triage creates no implementation issues.
• Re-runs supersede prior triage cleanly and are idempotent.

Size: M