⚡ Bolt: [Performance] Eliminate intermediate array allocations in tourism markers

[ClarusIubar]

💡 What: Refactored useNaverTourismMarkers.ts to replace multiple chained .map(), .filter(), and ...spread operations with highly efficient for loops.

🎯 Why: During rapid map panning, the hook rebuilt arrays of visible markers constantly. By creating numerous intermediate arrays for signatures, ID sets, and batched operation arrays, it created immense garbage collection (GC) pressure, which can cause micro-stutters during map interactions.

📊 Impact: Reduces memory allocations for the tourism layer reconciliation to near-zero intermediate arrays (O(1) temporary allocation vs O(N) multiplied by ~7 passes previously).

🔬 Measurement: Verifiable via memory allocation profiles in Chrome DevTools during continuous map panning across KTO tourism spots. Code correctness verified via npm run typecheck and npm run test:all.

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PR created automatically by Jules for task 7550674703007629157 started by @ClarusIubar

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