feat(clients): dual-OTP contact-change verification, webcam signature capture, and client history tab

Frontend counterpart to the backend dual-OTP contact-change feature:

- New ContactOtpBlockComponent (6-box segmented OTP input) used up to 4x in
  Edit Client (old/new mobile, old/new email — grouped under per-field
  sub-headers) and once each for mobile/email in Create Client, gating
  Save/Save & Next until every required box is verified.
- edit-client.component.ts: detects mobile/email/DOB changes against the
  loaded snapshot using local-date comparison (not `.toISOString()`, which
  false-triggers a day-shift in positive-UTC-offset timezones) and
  trimmed/case-insensitive email comparison (autofill whitespace or re-typed
  casing no longer reads as a change the masked preview can't explain).
- client-kyc-step.component.ts: new `invalidFieldLabels` getter names every
  currently-invalid required KYC field, surfaced via the Save & Next tooltip
  in both create-client and edit-client so a greyed-out button always
  explains what's still missing instead of a generic message.
- CaptureImageDialogComponent generalized for both profile photo and
  signature (photograph-a-paper-signature) capture:
  - Frame aspect now matches the requested getUserMedia resolution
    (4:3 profile / 16:9 signature) with object-fit: cover, eliminating the
    pillarboxing (black bars) a mismatched box previously caused.
  - Suppresses Chromium's auto-injected PiP/cast corner overlay icons.
  - Frame height capped in vh (not just px) so the dialog fits short
    viewports instead of pushing Cancel/Upload below the fold.
- upload-document-dialog.component.ts: generic Documents-tab upload now also
  offers "Capture from Webcam" alongside Browse, reusing the same capture
  dialog.
- New client History tab (reuses the existing Audit Trail data, scoped to
  this client) and dataUrlToFile/dataUrlToBlob util for routing webcam
  captures through the same upload pipelines as a picked file.

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

src/app/clients/clients-view/clients-view.component.ts

@@ -240,6 +240,9 @@ export class ClientsViewComponent implements OnInit {
       case 'Upload Signature':
         this.uploadSignature();
         break;
+      case 'Capture Signature':
+        this.captureSignatureImage();
+        break;
       case 'Delete Signature':
         this.deleteSignature();
         break;
@@ -332,6 +335,8 @@ export class ClientsViewComponent implements OnInit {
           this.uploadSignature();
         } else if (response.draw) {
           this.drawSignature();
+        } else if (response.capture) {
+          this.captureSignatureImage();
         } else if (response.delete) {
           this.deleteSignature();
         }
@@ -391,7 +396,9 @@ export class ClientsViewComponent implements OnInit {
    * Captures clients profile image.
    */
   private captureProfileImage() {
-    const captureImageDialogRef = this.dialog.open(CaptureImageDialogComponent);
+    const captureImageDialogRef = this.dialog.open(CaptureImageDialogComponent, {
+      data: { captureTarget: 'profile' }
+    });
     captureImageDialogRef.afterClosed().subscribe((imageURL: string) => {
       if (imageURL) {
         this.clientsService.uploadCapturedClientProfileImage(this.clientViewData.id, imageURL).subscribe(() => {
@@ -401,6 +408,24 @@ export class ClientsViewComponent implements OnInit {
     });
   }
 
+  /**
+   * Captures client signature via webcam (photograph of a paper signature).
+   * Mirrors `captureProfileImage()` — same dialog, parametrized for signature capture,
+   * uploaded via `uploadCapturedClientSignature()` instead of the profile-image upload.
+   */
+  private captureSignatureImage() {
+    const captureImageDialogRef = this.dialog.open(CaptureImageDialogComponent, {
+      data: { captureTarget: 'signature' }
+    });
+    captureImageDialogRef.afterClosed().subscribe((imageURL: string) => {
+      if (imageURL) {
+        this.clientsService.uploadCapturedClientSignature(this.clientViewData.id, imageURL).subscribe(() => {
+          this.reload();
+        });
+      }
+    });
+  }
+
   /**
    * Uploads the clients image.
    */