BUG-007 — Upper age boundary is not validated

Priority: Medium
Severity: Major
Environment: Chrome 128, desktop
Steps to reproduce:
1. Fill in all form fields with valid data
2. Enter 200 in the "Age" field
3. Click "Create account"
Expected result: Error "Age must be between 18 and 99"
Actual result: The form accepts the value 200; registration succeeds
Notes: The code only checks the lower bound (age <= 18); the upper bound (99) is never checked