feat: DEBT-014 + DEBT-029 Audit Infrastructure (Duplicate Detection & Event Logging)

DEBT-014: Duplicate detection & reconciliation tracking
- Create operation_audit_trail migration (0011)
- Hook OutboxPollerJob to detect and log duplicates
- Implement MetricsSql queries for duplicate/reconciliation metrics

DEBT-029: Audit trail consumer integration
- Create AuditTrailConsumer for event-driven audit logging
- Map 12+ event types to compliance.operation_audit_trail
- Register consumer in Program.cs DI and OutboxPollerJob

AGENTS.md v16.0 Compliance:
✅ Necessity: Both DEBT items from registry (2+3 pts)
✅ Simplicity: Event-driven via Outbox pattern (existing infra)
✅ Pattern: Vertical Slice consumer + SQL queries (established)
✅ Traceability: All event types documented and mapped
✅ Safety: Idempotent logging via ON CONFLICT DO NOTHING
✅ Maturity: Framework ready before feature implementation

Impact: Medium/High (5 pts total, Q3 target 4 pts exceeded)
Status: Code ready, awaiting SSH tunnel for migration test

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/KArtSell.DbMigrator/0011_create_operation_audit_trail.sql

@@ -0,0 +1,24 @@
+-- DEBT-014: Operation Audit Trail for Duplicate & Reconciliation Tracking
+
+CREATE SCHEMA IF NOT EXISTS compliance;
+
+CREATE TABLE IF NOT EXISTS compliance.operation_audit_trail (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    event_type VARCHAR(50) NOT NULL,
+    correlation_id UUID NOT NULL,
+    entity_type VARCHAR(50) NOT NULL,
+    entity_id UUID NOT NULL,
+    details JSONB,
+    detected_at TIMESTAMP NOT NULL DEFAULT NOW(),
+    resolved_by UUID,
+    resolved_at TIMESTAMP,
+    published_at TIMESTAMP NOT NULL DEFAULT NOW(),
+    revision INT NOT NULL DEFAULT 1,
+
+    CONSTRAINT fk_compliance_audit_trail_resolver
+        FOREIGN KEY (resolved_by) REFERENCES model_operations.approvers(id) ON DELETE SET NULL
+);
+
+CREATE INDEX idx_audit_trail_event_type ON compliance.operation_audit_trail(event_type, detected_at DESC);
+CREATE INDEX idx_audit_trail_correlation ON compliance.operation_audit_trail(correlation_id);
+CREATE INDEX idx_audit_trail_entity ON compliance.operation_audit_trail(entity_type, entity_id);