quality-gate: Add ZDP gate checklists and ACGCS integration

[AlexMikhalev]

Context

ZDP v2.2 (Zestic AI Development Process) defines 5 quality gates (PFA, LCO, LCA, IOC, FOC, CLR) with specific entry/exit criteria. The existing quality-gate skill handles engineering gates but lacks ZDP-specific checklists.

The Action-Centric Governance Control Surface (ACGCS) framework has been integrated into perspective-investigator and should be referenced here for gate items that are Contested or Underdetermined.

Changes Required

File: skills/quality-gate/skill.md
Type: Additive modification (~80 lines)

1. Add ## ZDP Quality Gates section after existing ## Essentialism Review
2. Include 6 gate checklists (PFA, LCO, LCA, IOC, FOC, CLR) with entry/exit criteria from ZDP Section 9
3. Add ## ACGCS Integration sub-section: Contested/Underdetermined items trigger escalation via perspective-investigation skill rather than forced pass/fail
4. Each checklist item supports epistemic status classification (Known/Sufficient, Partially Known, Contested, Underdetermined, Out-of-Scope)

Acceptance Criteria

• All 6 gate checklists present with correct entry/exit criteria
• ACGCS epistemic status classification documented
• Escalation path defined for Contested/Underdetermined items
• Existing gate logic unchanged (additive only)
• Cross-references to perspective-investigation skill

Priority

P2 -- Important enhancement

References

• Design doc: zestic-ai/claude-agents/docs/design-zdp-agents-and-skills.md (Change T1)
• ZDP v2.2 Section 9: Quality Gates & Reviews