fix: prevent stale search results from overwriting newer suggestions

[shivi14112007-create]

Closes #110

handleInputChange in LocationSearch.jsx debounced when a search fired, but had no mechanism to discard a result if a newer search had started before the older one resolved. Out-of-order network responses could cause stale suggestions to overwrite fresher ones.

Change:
Added a latestQueryRef that stamps the query associated with each debounced search as it fires. Before applying a result, the code checks whether latestQueryRef.current still matches the query that request was for — if a newer search has started since, the stale result is silently dropped instead of applied.

Testing:
Since the repo has no test framework set up yet (raised separately as its own issue), I verified manually by temporarily injecting an artificial 3s delay on a specific query in geocodingService.js to force out-of-order resolution:

• Typed "Lon" (triggering the artificially slow request), then quickly continued typing to "London" before the first request resolved.
• Before the fix: after ~3s, suggestions flipped back to stale "Lon" results.
• After the fix: the late "Lon" response was correctly ignored, and suggestions stayed matched to "London".
• Removed the temporary delay before committing this change.

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