feat(cost): add zombie hunter, Slack interactions, composite scoring

- Zombie resource hunter: detects idle EC2/RDS/EBS/EIP/NAT resources
- Slack interactive handler: acknowledge, snooze, create-ticket actions
- Composite anomaly scorer: Z-Score + rate-of-change + pattern + novelty
- Cold-start fast path for new resources (<7 days data)
- 005_zombies.sql migration

products/03-alert-intelligence/migrations/005_analytics.sql

@@ -0,0 +1,13 @@
+-- 005_analytics.sql
+-- Migration for MTTR and Noise Reduction Analytics
+
+-- Add resolved_at column for MTTR calculation (if not exists)
+ALTER TABLE incidents ADD COLUMN IF NOT EXISTS resolved_at TIMESTAMPTZ;
+
+-- Add pd_escalated_at column for PagerDuty auto-escalation idempotency
+ALTER TABLE incidents ADD COLUMN IF NOT EXISTS pd_escalated_at TIMESTAMPTZ;
+
+-- Add index on created_at for time-series queries (trends, noise stats)
+CREATE INDEX IF NOT EXISTS idx_incidents_created_at ON incidents(created_at);
+CREATE INDEX IF NOT EXISTS idx_alerts_received_at ON alerts(received_at);
+