fix: address cashbox-export whole-branch review findings

- Reject dates that are not strict YYYY-MM-DD (was accepting full ISO
  datetimes, which silently produced empty exports instead of a 400)
  and reject from > to with a 400 before touching the team/DB.
- Emit the cashbox_export_download and cashbox_export_subscription_update
  audit log events that were declared but never fired, matching the
  audit trail every sibling feature already has.
- Restore full type checking on the pdfkit import via `import = require()`
  instead of an untyped require() with an eslint-disable.
- Tighten a cashbox.spec.ts assertion to check the exact dialog class
  instead of expect.anything(), so it can't pass with the wrong dialog
  wired to the Export button.
- Style and announce the export dialogs' error messages using this
  codebase's established error-message/role=alert pattern.

myteamwallet_frontend_modern/src/app/features/team/cashbox/cashbox-export-dialog/cashbox-export-dialog.ts

@@ -30,7 +30,7 @@ const rangeValid: ValidatorFn = (group): ValidationErrors | null => {
     <form [formGroup]="form" (ngSubmit)="download()">
       <mat-dialog-content>
         @if (downloadError()) {
-          <p class="error">{{ downloadError() }}</p>
+          <p class="error-message" role="alert">{{ downloadError() }}</p>
         }
         <mat-form-field appearance="outline">
           <mat-label>Von</mat-label>
@@ -54,6 +54,14 @@ const rangeValid: ValidatorFn = (group): ValidationErrors | null => {
       </mat-dialog-actions>
     </form>
   `,
+  styles: `
+    .error-message {
+      padding: 12px 16px;
+      border-radius: 12px;
+      color: var(--mat-sys-error);
+      background: var(--mat-sys-error-container);
+    }
+  `,
 })
 export class CashboxExportDialog {
   protected readonly dialogRef = inject(MatDialogRef<CashboxExportDialog>);

myteamwallet_frontend_modern/src/app/features/team/cashbox/cashbox-export-subscription-dialog/cashbox-export-subscription-dialog.html

@@ -1,10 +1,10 @@
 <h2 mat-dialog-title>Automatischen Versand einrichten</h2>
 <mat-dialog-content>
   @if (loadError()) {
-    <p class="error">{{ loadError() }}</p>
+    <p class="error-message" role="alert">{{ loadError() }}</p>
   }
   @if (saveError()) {
-    <p class="error">{{ saveError() }}</p>
+    <p class="error-message" role="alert">{{ saveError() }}</p>
   }
   <mat-form-field appearance="outline">
     <mat-label>E-Mail-Adresse hinzufügen</mat-label>

myteamwallet_frontend_modern/src/app/features/team/cashbox/cashbox-export-subscription-dialog/cashbox-export-subscription-dialog.scss

@@ -0,0 +1,6 @@
+.error-message {
+  padding: 12px 16px;
+  border-radius: 12px;
+  color: var(--mat-sys-error);
+  background: var(--mat-sys-error-container);
+}

myteamwallet_frontend_modern/src/app/features/team/cashbox/cashbox-export-subscription-dialog/cashbox-export-subscription-dialog.ts

@@ -27,6 +27,7 @@ const EMAIL_PATTERN = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
     MatSlideToggleModule,
   ],
   templateUrl: './cashbox-export-subscription-dialog.html',
+  styleUrl: './cashbox-export-subscription-dialog.scss',
 })
 export class CashboxExportSubscriptionDialog {
   protected readonly dialogRef = inject(MatDialogRef<CashboxExportSubscriptionDialog>);

myteamwallet_frontend_modern/src/app/features/team/cashbox/cashbox.spec.ts

@@ -8,6 +8,7 @@ import { PenaltyApi } from '../../../core/team/penalty-api';
 import { TeamStore } from '../../../core/team/team-store';
 import { TransactionsApi } from '../../../core/team/transactions-api';
 import { Cashbox } from './cashbox';
+import { CashboxExportDialog } from './cashbox-export-dialog/cashbox-export-dialog';
 
 describe('Cashbox', () => {
   const team = {
@@ -292,7 +293,7 @@ describe('Cashbox', () => {
     exportButton?.click();
 
     expect(dialog.open).toHaveBeenCalledWith(
-      expect.anything(),
+      CashboxExportDialog,
       expect.objectContaining({ data: { teamId: expect.any(Number) } }),
     );
   });