Add Data Validation Rules

[codewizdave]

Description

Currently, there's minimal validation on data entry. Proper validation would prevent:

• Invalid email formats
• Future dates for past events
• Duplicate entries
• Missing required fields

Requirements

1. Field Validation:

   • Email format validation
   • Phone number format
   • Date logic (end date > start date)
   • Required fields enforced

2. Duplicate Prevention:

   • Warn when creating employee with same name
   • Check for duplicate contract dates

3. Visual Feedback:

   • Show validation errors inline
   • Prevent form submission until valid

Technical Notes

Use Zod schemas (already in use) for validation on both client and server.

Acceptance Criteria

• Required fields are enforced
• Invalid formats show error messages
• Can't save invalid data