Multi-turn pressure evidence

[SSBrouhard]

Goal

Emit multi-turn pressure and escalation signals as first-class VMGA evidence events. VMGA already counts denials toward lockdown; this issue tracks making the escalation pattern itself inspectable in evidence.

Scope

Capture structured evidence for repeated denied attempts, urgency or authority-spoof escalation, and proposal-mutation attempts across a request lifecycle. Reference ContentRisk signals where applicable, but do not create a parallel policy engine.

Acceptance sketch

• Repeated denied attempts are represented as structured evidence, not only counters.
• Urgency/authority-spoof escalation and proposal mutation attempts are detectable in evidence.
• Evidence carries correlation/proposal context so an operator can trace the multi-turn pattern.
• Existing denial-count lockdown behavior remains intact.
• Tests cover at least one repeated-denial escalation and one proposal-mutation attempt.

[SSBrouhard]

Created as a scoped follow-up from approval-signing design PR #27. This should add multi-turn pressure/escalation signals as first-class evidence while preserving existing denial-count lockdown behavior.