[Bug]: Onboarding College Manual Input Validation Leak #210

Bug Description

• Description:
  If a user types a search string into the college input, closes the dropdown without clicking an item, and clicks submit, the text box allows submission of invalid manual entries that are not present in the colleges database list.
• Proposed Solution:
  • In Onboarding.jsx, validate that selectedCollege matches a value in collegesList or is explicitly set to "Other" before submitting.
• Acceptance Criteria:
  • Form submission blocks invalid manual typing that doesn't correspond to listed colleges.