Fix pest farming performance + improve rate impact display

[lixckxx]

Fix pest farming performance + improve rate impact display

Changes:

• Replaced repeated toLocaleString calls with a cached Intl.NumberFormat map in +page.svelte and pest-rate-breakdown.svelte to avoid recreating formatters on every call
• Moved inline .filter().sort() pet chain into a derived sortedPets = $derived.by() field in PestFarmingPageContext, so sorting and filtering run reactively instead of on every render
• Added #lastRateStateKey, #lastGearRateStateKey, and #lastPetRateStateKey fields to handle state-based cache invalidation, replacing the previous size-threshold cache clears (>500 / >1000 entries)
• Hoisted state-key checks to the top of getPhasePieceRateImpact, getSharedEquipmentPieceRateImpact, and getPetRateImpact, before cache lookup, so stale entries are invalidated immediately after state changes
• Moved memo clearing in #calculatePestRateImpact to occur before cache lookup, keyed on result.stateKey, ensuring the cache is reset before new entries are stored
• Refactored getPestRateImpact and rateImpactItems to reuse the existing pestRateCalculator and pestRateResult derived values instead of instantiating a new calculator and recomputing on every call
• Introduced #itemPriceCache in PestFarmingPageContext so pestRatePriceBook only fetches sell values for new item IDs, skipping previously resolved items
• Replaced Math.min(...auctionPrices) with a reduce() to avoid spreading large arrays into function calls, and simplified bazaar/auction selection logic into a direct comparison
• Replaced triple spread-into-Set pattern in neededItems with sequential Set.add() calls to reduce intermediate allocations during recomputation

[brettt89]

Did you intend to delete the .env.example file?

[lixckxx]

no, thats my bad, thought i didnt include that change when i pushed