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).

frontend/src/components/pages/ReportingPage.js

@@ -1261,16 +1261,31 @@ function TableCell({ colKey, finding, canWrite, onCveMouseEnter, onCveMouseLeave
                     }
                 />
             );
-        case 'ipAddress':
+        case 'ipAddress': {
+            // Display priority: IPv4 > Qualys IPv6 > Primary IPv6
+            const displayIp = finding.ipAddress || finding.qualysIpv6 || finding.primaryIpv6 || '';
+            const ipSource = finding.ipAddress ? null : finding.qualysIpv6 ? 'Q' : finding.primaryIpv6 ? 'v6' : null;
+            const hoverIp = displayIp || null;
             return (
                 <td
-                    style={{ padding: '0.45rem 0.75rem', whiteSpace: 'nowrap', color: '#94A3B8', fontFamily: 'monospace', fontSize: '0.72rem', cursor: finding.ipAddress ? 'help' : 'default' }}
-                    onMouseEnter={onIpMouseEnter && finding.ipAddress ? (e) => onIpMouseEnter(finding.ipAddress, e, finding.hostId) : undefined}
+                    style={{ padding: '0.45rem 0.75rem', whiteSpace: 'nowrap', color: '#94A3B8', fontFamily: 'monospace', fontSize: '0.72rem', cursor: hoverIp ? 'help' : 'default' }}
+                    onMouseEnter={onIpMouseEnter && hoverIp ? (e) => onIpMouseEnter(hoverIp, e, finding.hostId) : undefined}
                     onMouseLeave={onIpMouseLeave || undefined}
+                    title={ipSource === 'Q' ? 'Qualys IPv6 (no IPv4 available)' : ipSource === 'v6' ? 'Primary IPv6 (no IPv4 available)' : undefined}
                 >
-                    {finding.ipAddress || '—'}
+                    {displayIp ? (
+                        <>
+                            <span style={{ maxWidth: '140px', overflow: 'hidden', textOverflow: 'ellipsis', display: 'inline-block', verticalAlign: 'middle' }}>{displayIp}</span>
+                            {ipSource && (
+                                <span style={{ marginLeft: '0.3rem', fontSize: '0.55rem', padding: '0.08rem 0.25rem', borderRadius: '0.2rem', background: ipSource === 'Q' ? 'rgba(245, 158, 11, 0.15)' : 'rgba(99, 102, 241, 0.15)', border: ipSource === 'Q' ? '1px solid rgba(245, 158, 11, 0.4)' : '1px solid rgba(99, 102, 241, 0.4)', color: ipSource === 'Q' ? '#FBBF24' : '#A5B4FC', fontWeight: '700', verticalAlign: 'middle' }}>
+                                    {ipSource}
+                                </span>
+                            )}
+                        </>
+                    ) : '—'}
                 </td>
             );
+        }
         case 'dns':
             return (
                 <OverrideCell