refactor: add proper types, fix zod error handling, and simplify import mapping logic

src/lib/actions/import.actions.ts

@@ -2,9 +2,18 @@
 
 import { revalidatePath } from "next/cache"
 import Papa from "papaparse"
+import { flattenError } from "zod"
 
 import { type ImportFormType, importSchema } from "@/lib/schemas/import.schemas"
-import type { ImportItem } from "@/lib/types"
+import type { CreateMovementFormType } from "@/lib/schemas/movement.schemas"
+import type {
+  Asset,
+  Assignment,
+  Category,
+  ImportItem,
+  Item,
+  Recipient,
+} from "@/lib/types"
 import { AssetService } from "@/services/asset.service"
 import { AssignmentService } from "@/services/assignment.service"
 import { CategoryService } from "@/services/category.service"
@@ -17,7 +26,7 @@ export async function importItems(formData: ImportFormType) {
 
   if (!validatedFields.success) {
     return {
-      errors: validatedFields.error.flatten().fieldErrors,
+      errors: flattenError(validatedFields.error).fieldErrors,
     }
   }
 
@@ -155,7 +164,7 @@ export async function importItems(formData: ImportFormType) {
       importErrors.push(`Row ${index + 2}: Category or categoryId is required`)
     }
 
-    if (stock && isNaN(Number(stock))) {
+    if (stock && Number.isNaN(stock)) {
       importErrors.push(`Row ${index + 2}: Stock must be a number`)
     }
 
@@ -202,7 +211,7 @@ export async function importItems(formData: ImportFormType) {
       categoryId: categoryId ? categoryId : row.categoryId?.trim() || "",
       category: row.category?.trim() || "",
       deliveryNote: row.deliveryNote?.trim() || "",
-      assigned: row.assigned?.trim() === "true" ? true : false,
+      assigned: row.assigned?.trim() === "true",
       username: row.username?.trim() || "",
       firstName: row.firstName?.trim() || "",
       lastName: row.lastName?.trim() || "",
@@ -224,11 +233,11 @@ export async function importItems(formData: ImportFormType) {
     } = item
 
     // Reset variables at the beginning of each iteration
-    let newItem
+    let newItem: Item | null = null
-    let newAsset
+    let newAsset: Asset | null = null
-    let newCategory
+    let newCategory: Category | null = null
-    let newRecipient
+    let newRecipient: Recipient | null = null
-    let newAssignment
+    let newAssignment: Assignment | null = null
 
     const existingCategory = categoryId
       ? await CategoryService.findById(categoryId)
@@ -307,7 +316,7 @@ export async function importItems(formData: ImportFormType) {
       })
     }
 
-    const movementData: any = {
+    const movementData: CreateMovementFormType = {
       assetId: newAsset?.id || undefined,
       quantity: stock || 1,
       type: assigned ? "ASSIGNMENT" : "IN",