Add vitest for supporting test coverage

• Setup tests using vitest framework.
• Create tests using AAA pattern (Arrange, Act, Assert).
• Tests cases to be covered are,
  • feature: Patient Search during patient registration
    • Form Rendering: Verifies that search form elements render correctly
    • Results Display: Tests that search results are displayed when patients are found
    • No Results Message: Confirms the "no patients found" message appears when search returns empty results
    • Loading State: Tests that the loading state is properly displayed during search operations
    • Patient Selection: Ensures the onPatientSelect callback is called when a patient result is clicked
    • Search Type Selection: Verifies that different search types (book_no, phone, name) work correctly
    • Keyboard Support: Tests that pressing Enter triggers the search functionality