Add IPv6 fallback display for findings without IPv4

Findings with no IPv4 address now display Qualys IPv6 or Primary IPv6 as
fallback in the IP column, with a badge indicator:
  - 'Q' (amber) = Qualys IPv6 from hostAdditionalDetails
  - 'v6' (indigo) = Primary IPv6 from assetCustomAttributes

Priority: IPv4 > Qualys IPv6 > Primary IPv6

Backend changes:
- extractFinding now captures qualysIpv6 and primaryIpv6
- New extractQualysIpv6 helper parses hostAdditionalDetails
- upsertFindingsBatch stores both fields
- API response includes qualysIpv6 and primaryIpv6
- Migration adds qualys_ipv6 and primary_ipv6 columns

The Qualys IPv6 is preferred over Primary IPv6 because it resolves in CARD
(confirmed via testing with PMADEV-1).

backend/migrations/run-all.js

@@ -30,6 +30,7 @@ const POSTGRES_MIGRATIONS = [
     'add_queue_remediation_notes_table.js',
     'add_remediate_workflow_type.js',
     'add_notifications_table.js',
+    'add_ivanti_findings_ipv6_columns.js',
 ];
 
 async function runAll() {