fix: nominee share & joint ownership validation across all account types

- Block 0% nominee share in all steppers (Savings, FD, RD, Current) —
  Add button disabled via isValid, addNominee() guards < 1, nominee-form
  error condition fixed for value=0
- Joint ownership: default primary share 50%, enforce min 1% on blur,
  max 100% on input with DOM clamp via $event, auto-redistribute
  co-holders proportionally when primary share changes,
  isJointOwnershipValid guards each holder >= 1
- Pending/Rejected account tabs: normalize date format to 22 May 2026
  for both array and string date values from API

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/current-accounts/current-account-stepper/current-account-currency-step/current-account-currency-step.component.html

@@ -123,7 +123,12 @@
               <button type="button" class="nom-cancel-btn" (click)="showNomineeForm = false; nomineeError = ''">
                 Cancel
               </button>
-              <button type="button" class="nom-confirm-btn" (click)="addNominee()">
+              <button
+                type="button"
+                class="nom-confirm-btn"
+                [disabled]="!nomineeFormComp?.isValid"
+                (click)="addNominee()"
+              >
                 <i class="fas fa-plus"></i> Add
               </button>
             </div>

src/app/current-accounts/current-account-stepper/current-account-currency-step/current-account-currency-step.component.ts

@@ -83,6 +83,10 @@ export class CurrentAccountCurrencyStepComponent implements OnChanges {
         return;
       }
     }
+    if (!data.percentageShare || data.percentageShare < 1) {
+      this.nomineeError = 'Share must be at least 1%.';
+      return;
+    }
     const newTotal = this.totalShare + (+data.percentageShare || 0);
     if (newTotal > 100) {
       this.nomineeError = `Total share cannot exceed 100%. Remaining: ${this.remainingShare}%`;