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/DebtCategoryController.ts

@@ -6,13 +6,19 @@ import {z} from 'zod';
 const createCategorySchema = z.object({
   name: z.string().min(1).max(255),
   description: z.string().optional(),
-  color: z.string().regex(/^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$/).optional(),
+  color: z
+    .string()
+    .regex(/^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$/)
+    .optional()
 });
 
 const updateCategorySchema = z.object({
   name: z.string().min(1).max(255).optional(),
   description: z.string().optional(),
-  color: z.string().regex(/^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$/).optional(),
+  color: z
+    .string()
+    .regex(/^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$/)
+    .optional()
 });
 
 /**