fix(clients): minor-age threshold to 18, senior/PWD doc reload, in-app document preview dialog

- Raise isMinor threshold from age <10 to <18 (legal definition), cascading correctly to
  guardian requirement, KYC document filtering, and Education Level/Degree Qualification
  visibility (now shown for all ages, not hidden for minors).
- Load and display previously-uploaded Senior Citizen proof / PWD certificate documents on
  edit (view/replace/remove), instead of always showing an empty upload prompt.
- Fix seniorPwdDocsComplete to accept an existing certificate, not just a freshly-picked file.
- Add DocumentPreviewDialogComponent: a reusable in-app modal (image/PDF/download) used in
  place of window.open() for saved KYC/address/senior-citizen/PWD documents — avoids popup
  blockers (fired only after the async download resolved) and Chrome/Edge's failure to paint
  large base64 data: URLs on first open.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/clients/client-stepper/client-india-address-step/client-india-address-step.component.ts

@@ -15,9 +15,11 @@ import { MatCheckbox } from '@angular/material/checkbox';
 import { MatTabsModule } from '@angular/material/tabs';
 import { MatIcon } from '@angular/material/icon';
 import { MatIconButton, MatButton } from '@angular/material/button';
+import { MatDialog } from '@angular/material/dialog';
 import { ClientsService } from '../../clients.service';
 import { ProofType, normalizeProofType, groupProofsByCategory } from '../../shared/kyc-proof-types';
 import { KycUploadHelperService } from '../../shared/kyc-upload-helper.service';
+import { DocumentPreviewDialogComponent } from '../../shared/document-preview-dialog/document-preview-dialog.component';
 
 @Component({
   selector: 'mifosx-client-india-address-step',
@@ -38,6 +40,7 @@ export class ClientIndiaAddressStepComponent implements OnInit, OnChanges {
   private http = inject(HttpClient);
   private clientsService = inject(ClientsService);
   private kycUpload = inject(KycUploadHelperService);
+  private dialog = inject(MatDialog);
 
   /** Client ID — when set, loads existing addresses for edit mode */
   @Input() clientId: string = '';
@@ -633,33 +636,17 @@ export class ClientIndiaAddressStepComponent implements OnInit, OnChanges {
     });
   }
 
-  /**
-   * Open the saved address proof in a new browser tab.
-   *
-   * For images we already hold a base64 data URL in `previewUrl` from
-   * `loadExistingAddressProof`, so we can hand it straight to `window.open`.
-   * For PDFs / other types we need to fetch the binary blob and create a
-   * temporary object URL so the browser's PDF viewer can render it.
-   */
+  /** Open the saved address proof in an in-app preview dialog. */
   viewExistingAddressProof(): void {
     if (!this.existingAddressProofIdentifierId || this.existingAddressProofDocuments.length === 0) {
       return;
     }
     const doc = this.existingAddressProofDocuments[0];
-    if (doc.previewUrl) {
-      window.open(doc.previewUrl, '_blank', 'noopener');
-      return;
-    }
     this.clientsService.downloadClientIdentificationDocument(this.existingAddressProofIdentifierId, doc.id).subscribe({
-      next: (blob: Blob) => {
-        const url = URL.createObjectURL(blob);
-        const w = window.open(url, '_blank', 'noopener');
-        // Revoke after the tab has had time to load — browsers vary, so
-        // err on the side of a generous wait.
-        if (w) {
-          setTimeout(() => URL.revokeObjectURL(url), 60_000);
-        }
-      },
+      next: (blob: Blob) =>
+        this.dialog.open(DocumentPreviewDialogComponent, {
+          data: { blob, title: doc.fileName || doc.name, fileName: doc.fileName || doc.name }
+        }),
       error: () => {
         // Silent fail — UI shows the saved name so user knows it exists.
       }