feat: Implement air-gap functionality with timeline impact and evidence snapshot services

- Added AirgapTimelineImpact, AirgapTimelineImpactInput, and AirgapTimelineImpactResult records for managing air-gap bundle import impacts.
- Introduced EvidenceSnapshotRecord, EvidenceSnapshotLinkInput, and EvidenceSnapshotLinkResult records for linking findings to evidence snapshots.
- Created IEvidenceSnapshotRepository interface for managing evidence snapshot records.
- Developed StalenessValidationService to validate staleness and enforce freshness thresholds.
- Implemented AirgapTimelineService for emitting timeline events related to bundle imports.
- Added EvidenceSnapshotService for linking findings to evidence snapshots and verifying their validity.
- Introduced AirGapOptions for configuring air-gap staleness enforcement and thresholds.
- Added minimal jsPDF stub for offline/testing builds in the web application.
- Created TypeScript definitions for jsPDF to enhance type safety in the web application.

deploy/helm/stellaops/templates/externalsecrets.yaml

@@ -0,0 +1,28 @@
+{{- if and .Values.externalSecrets.enabled .Values.externalSecrets.secrets }}
+{{- range $secret := .Values.externalSecrets.secrets }}
+apiVersion: external-secrets.io/v1beta1
+kind: ExternalSecret
+metadata:
+  name: {{ include "stellaops.fullname" $ }}-{{ $secret.name }}
+  labels:
+    {{- include "stellaops.labels" $ | nindent 4 }}
+spec:
+  refreshInterval: {{ default "1h" $secret.refreshInterval }}
+  secretStoreRef:
+    name: {{ $secret.storeRef.name }}
+    kind: {{ default "ClusterSecretStore" $secret.storeRef.kind }}
+  target:
+    name: {{ $secret.target.name | default (printf "%s-%s" (include "stellaops.fullname" $) $secret.name) }}
+    creationPolicy: {{ default "Owner" $secret.target.creationPolicy }}
+  data:
+    {{- range $secret.data }}
+    - secretKey: {{ .key }}
+      remoteRef:
+        key: {{ .remoteKey }}
+        {{- if .property }}
+        property: {{ .property }}
+        {{- end }}
+    {{- end }}
+---
+{{- end }}
+{{- end }}