Add lock files for package management and update architecture documentation

- Introduced bun.lock and package-lock.json to manage dependencies for the project.
- Enhanced backend API architecture documentation with additional security and documentation guidelines.
- Made minor formatting adjustments across various files for consistency and clarity.

backend-api/src/controllers/DebtPaymentController.ts

@@ -7,7 +7,7 @@ const createPaymentSchema = z.object({
   accountId: z.string().uuid(),
   amount: z.number().min(0.01),
   paymentDate: z.string().transform(str => new Date(str)),
-  notes: z.string().optional(),
+  notes: z.string().optional()
 });
 
 /**
@@ -46,11 +46,7 @@ export class DebtPaymentController {
     }
 
     if (startDate && endDate) {
-      const payments = await this.paymentService.getByDateRange(
-        userId,
-        new Date(startDate),
-        new Date(endDate)
-      );
+      const payments = await this.paymentService.getByDateRange(userId, new Date(startDate), new Date(endDate));
       return reply.send({payments});
     }