removed default

Co-authored-by: Copilot <copilot@github.com>

src/app/pages/create-page/create-page.ts

@@ -66,7 +66,7 @@ export class CreatePage {
   minAmount = signal<number>(30);
   maxAmount = signal<number>(200_000);
 
-  amount = signal<number>(100);
+  amount = signal<number | null>(null);
   note = signal<string>('');
   error = signal<string>('');
   loading = signal<boolean>(false);
@@ -122,11 +122,11 @@ export class CreatePage {
 
   createCheck(): void {
     const val = this.amount();
-    if (!val || val < this.minAmount()) {
+    if (val !== null && val < this.minAmount()) {
       this.error.set(`${this.t('errors.invalid_amount')} (мин. ${this.minAmount()} ₽)`);
       return;
     }
-    if (val > this.maxAmount()) {
+    if (val !== null && val > this.maxAmount()) {
       this.error.set(`${this.t('errors.invalid_amount')} (макс. ${this.maxAmount().toLocaleString('ru')} ₽)`);
       return;
     }
@@ -145,7 +145,7 @@ export class CreatePage {
         `${QR_VITANOVA_API}/qr`,
         {
           qrtype: 'QRDynamic',
-          amount: val,
+          ...(val !== null ? { amount: val } : {}),
           currency: this.currency(),
           partnerqrID,
           qrDescription: this.note().trim(),
@@ -225,7 +225,7 @@ export class CreatePage {
             this.store.setCreated({
               fastcheck: res.fastcheck,
               code: res.code,
-              amount: this.amount(),
+              amount: this.amount() ?? null,
               expiration: res.expiration
             });
           }
@@ -235,9 +235,9 @@ export class CreatePage {
       });
   }
 
-  onAmountChange(value: number): void {
-    this.amount.set(value);
-    if (value > 0) this.error.set('');
+  onAmountChange(value: number | null): void {
+    this.amount.set(value || null);
+    if (value && value > 0) this.error.set('');
   }
 
   onNoteChange(value: string): void {