[cschanhniem]

Implements R3 from NEXT_100_PR_MAP.

What

• src/openamp_foundry/evidence/audit_trail_report.py: ATR- schema; AuditTrailReport dataclass (15 fields); validate_audit_trail_report(); build_audit_trail_report() (auto-computes n_stages_complete, enforces dry_lab_only=True); format_audit_trail_report()
• REQUIRED_ATR_STAGES (5): BSP, WHR, PCU, HCR, PQG
• VALID_TRAIL_COMPLETENESS_STATUSES (4): complete, partial, broken_chain, dry_lab_only
• VALID_CHAIN_INTEGRITY_GRADES (5): A, B, C, D, N/A
• tests/evidence/test_audit_trail_report.py: 63 tests in 5 classes
• BASELINE: 9026 → 9089

Disconfirming pass

• dry_lab_only=False blocked (tested) — audit trail is a documentation artifact
• TOY- candidate_family_id blocked (tested)
• complete status enforces all 5 stages individually (tested)
• complete status blocks missing_stages (tested)
• complete status blocks chain_link_failures (tested)
• dry_lab_only status blocks WHR/PCU/HCR/PQG (tested)
• grade D incompatible with complete status (tested)
• grade A requires complete or partial status (tested)
• build() auto-computes n_stages_complete from actual record lists (tested)