feat: implement login functionality with error handling and session management

Frontend/erp-system/lib/validations.ts

@@ -15,21 +15,14 @@ export const emailSchema = z.preprocess(
 	z.string().min(1, "Email is required").email("Enter a valid email")
 )
 
-// Login schema (email + password) for reuse across the app
+// Login schema (email + password) for reuse across the app.
+// Password strength is intentionally NOT re-validated here: an existing
+// account's password may predate current complexity rules, and only the
+// server can judge whether credentials are actually correct. Complexity
+// rules belong on registration/reset-password, not on login.
 export const loginSchema = z.object({
 	email: emailSchema,
-	password: requiredString("Password is required")
-		.refine((val) => val.length >= 8, { message: "Password must be at least 8 characters" })
-		.refine((val) => /[A-Z]/.test(val), {
-			message: "Password must contain at least one uppercase letter",
-		})
-		.refine((val) => /[a-z]/.test(val), {
-			message: "Password must contain at least one lowercase letter",
-		})
-		.refine((val) => /[0-9]/.test(val), { message: "Password must contain at least one number" })
-		.refine((val) => /[!@#$%^&*(),.?":{}|<>\[\]\\/`~;'+=-]/.test(val), {
-			message: "Password must contain at least one special character",
-		}),
+	password: requiredString("Password is required"),
 })
 
 export type LoginValues = z.infer<typeof loginSchema>