fix: Add DELETE endpoint for credit notes applied invoices

- Add missing DELETE /credit-notes/applied-invoices/:id endpoint
- Fix CreditNotesApplyInvoice controller to use correct service methods
- Add missing GetCreditNoteAssociatedInvoicesToApply endpoint
- Add proper DTO for ApplyCreditNoteToInvoices
- Update frontend creditNote hook to use correct API paths

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

packages/server/src/modules/CreditNotesApplyInvoice/dtos/ApplyCreditNoteToInvoices.dto.ts

@@ -0,0 +1,38 @@
+import { ApiProperty } from '@nestjs/swagger';
+import { Type } from 'class-transformer';
+import {
+  ArrayMinSize,
+  IsArray,
+  IsInt,
+  IsNotEmpty,
+  IsNumber,
+  ValidateNested,
+} from 'class-validator';
+
+export class ApplyCreditNoteInvoiceEntryDto {
+  @IsNotEmpty()
+  @IsInt()
+  @ApiProperty({ description: 'Invoice ID to apply credit to', example: 1 })
+  invoiceId: number;
+
+  @IsNotEmpty()
+  @IsNumber()
+  @ApiProperty({ description: 'Amount to apply', example: 100.5 })
+  amount: number;
+}
+
+export class ApplyCreditNoteToInvoicesDto {
+  @IsArray()
+  @ArrayMinSize(1)
+  @ValidateNested({ each: true })
+  @Type(() => ApplyCreditNoteInvoiceEntryDto)
+  @ApiProperty({
+    description: 'Entries of invoice ID and amount to apply',
+    type: [ApplyCreditNoteInvoiceEntryDto],
+    example: [
+      { invoice_id: 1, amount: 100.5 },
+      { invoice_id: 2, amount: 50 },
+    ],
+  })
+  entries: ApplyCreditNoteInvoiceEntryDto[];
+}