feat: rename 'fee' to 'unitPrice' across purchase components and models

- Updated form component to use 'unitPrice' instead of 'fee'.
- Adjusted product charge row form fields and templates to reflect the new naming.
- Modified receipt template and related components to utilize 'unitPrice'.
- Changed models and interfaces to replace 'fee' with 'unitPrice'.
- Updated supplier invoice and statistics components to align with the new naming convention.
- Added new API routes for dashboard and statistics modules.

src/app/shared/components/purchaseReceiptPayment/wrapper.component.html

@@ -5,5 +5,6 @@
     [supplierId]="purchaseReceipt.supplierId.toString()"
     [inventoryId]="purchaseReceipt.inventoryId.toString()"
     [invoiceId]="purchaseReceipt.id.toString()"
+    (onSubmit)="submitted()"
   />
 }