added Validation rules

backend/src/middleware/Validation/Authentication.md

@@ -1,12 +1,19 @@
 ## Authentication
 
 ### \[ACTION: login\]
-* Requires valid email and password format
+* Requires valid email and password format:
+  - Minimum 8 characters
+  - Must contain uppercase, lowercase, number and special character
 * Server validates credentials before issuing token
 * Token and employee data stored in localStorage upon success
 
 ### \[ACTION: register\]
-* Requires email, password, and name
+* `Password` optional but strict validation:
+  - Minimum 8 characters
+  - Must contain uppercase, lowercase, number and special character
+* `firstname` 1-100 characters and must not be empty
+* `lastname` 1-100 characters and must not be empty
+* Requires valid email
 * Role is optional during registration
 * Automatically logs in user after successful registration