test : added unit tests for hooks/useSiteSearch hook - #10

Summary of What Has Been Done

Created hooks/useSiteSearch.test.ts with comprehensive unit tests covering:

• Returns empty initial state (query='', results=[], hasQuery=false)
• setQuery updates query immediately
• hasQuery is true when query has non-whitespace content
• hasQuery is false for whitespace-only query
• clear resets query, results, and hasQuery to initial state
• Results reflect the debounced query via searchDomains
• Returns empty results for non-matching query
• isSearching is false initially and when query matches debounced value
• Custom domains passed via the domains parameter are used for searching
• Multiple setQuery calls update state each time

Mocked useDebounce from @/hooks/useDebounce to return the value immediately (bypassing the 120ms delay) and mocked searchDomains from @/lib/search/fuzzySearch for controlled fixture data.

Changes Made

• New file: hooks/useSiteSearch.test.ts

Impact it Made

Adds first unit test coverage for the useSiteSearch hook, ensuring the search state management and result filtering work correctly under rapid input scenarios.

Closes #8425.

Note: please assign this PR to the tmdeveloper007 account.