feat: add IP address logging to webhooks for whitelisting

Implements comprehensive IP logging for webhook requests to enable
IP whitelisting and security monitoring.

Features:
- Capture source IP from webhook requests (x-forwarded-for, x-real-ip)
- Capture user agent for identification
- Store in webhook_logs table
- New API endpoint: GET /api/webhooks/ips
- View unique IPs with request counts and statistics
- Identify Autotask IPs for whitelisting

Database Changes:
- Added source_ip column (VARCHAR 45) to webhook_logs
- Added user_agent column (TEXT) to webhook_logs
- Added index on source_ip for efficient queries
- Migration 005 for existing installations

API Endpoints:
- GET /api/webhooks/ips?hours=168&entityType=Tickets
  Returns unique IPs with:
  * Request counts (total, successful, failed)
  * First/last seen timestamps
  * Entity types accessed
  * User agent strings

Use Cases:
1. Identify Autotask webhook IPs
2. Configure IP whitelist in nginx/Pangolin/Cloudflare
3. Monitor for unauthorized webhook attempts
4. Audit webhook sources
5. Detect IP changes from Autotask

Security Benefits:
- Enable IP whitelisting for webhook endpoint
- Block unauthorized webhook attempts
- Monitor for suspicious activity
- Audit trail of webhook sources

Documentation:
- Complete IP whitelisting guide (WEBHOOK_IP_WHITELISTING.md)
- Configuration examples for nginx, Pangolin, Cloudflare
- Monitoring queries and best practices
- Troubleshooting guide

Files Modified:
- migrations/004_webhook_support.sql - Added IP columns
- migrations/005_add_webhook_ip_logging.sql - Migration for existing installs
- lib/types/webhook.ts - Added IP fields to WebhookLog
- lib/services/webhook-service.ts - Capture and log IPs
- app/api/webhooks/autotask/route.ts - Extract IP from headers
- app/api/webhooks/ips/route.ts - New IP viewing endpoint
- docs/WEBHOOK_IP_WHITELISTING.md - Complete guide

Next Steps:
1. Run migration (004 for new, 005 for existing)
2. Deploy updated code
3. Receive webhooks from Autotask
4. View IPs via /api/webhooks/ips
5. Configure IP whitelist in proxy/tunnel

migrations/005_add_webhook_ip_logging.sql

@@ -0,0 +1,35 @@
+-- Migration: Add IP logging to webhook_logs
+-- Description: Add source_ip and user_agent columns for IP whitelisting
+
+-- Add source_ip column if it doesn't exist
+DO $$ 
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.columns 
+    WHERE table_name = 'webhook_logs' AND column_name = 'source_ip'
+  ) THEN
+    ALTER TABLE webhook_logs ADD COLUMN source_ip VARCHAR(45);
+    COMMENT ON COLUMN webhook_logs.source_ip IS 'Source IP address of webhook request (IPv4 or IPv6)';
+  END IF;
+END $$;
+
+-- Add user_agent column if it doesn't exist
+DO $$ 
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.columns 
+    WHERE table_name = 'webhook_logs' AND column_name = 'user_agent'
+  ) THEN
+    ALTER TABLE webhook_logs ADD COLUMN user_agent TEXT;
+    COMMENT ON COLUMN webhook_logs.user_agent IS 'User agent string from webhook request';
+  END IF;
+END $$;
+
+-- Add index on source_ip for efficient IP-based queries
+CREATE INDEX IF NOT EXISTS idx_webhook_logs_source_ip ON webhook_logs(source_ip);
+
+-- Verify columns were added
+SELECT column_name, data_type 
+FROM information_schema.columns 
+WHERE table_name = 'webhook_logs' 
+  AND column_name IN ('source_ip', 'user_agent');