Add Doppler Phase to Search Link

[GODrums]

As our market searches now support an extended MHN format, we can switch to get more accurate results for Doppler knives.

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Note

Enhances the listing modal's search link to include Doppler phase when applicable and makes itemInfo optional.

• Frontend:
  • List item modal (src/lib/components/inventory/list_item_modal.ts):
    • Enhance searchUrl to append Doppler phase to market_hash_name when applicable using hasDopplerPhase/getDopplerPhase, then URL-encode the extended value.
    • Make itemInfo optional to safely access paintindex.
    • Import Doppler utilities from utils/dopplers.

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