Add inventory cache with forceRefreshInventory support

[LinaBell]

Summary

• Add 6h TTL in-memory cache for ecosystem inventory items to reduce API calls
• Wire up forceRefreshInventory from client URL params through to the server cache
• Both getInventoryItems and awardBadge now use the shared cache instead of direct Ecosystem.create calls

Test plan

• Load game state — badges should render correctly from cached inventory
• Append ?forceRefreshInventory=true to the app URL — server should bypass cache and fetch fresh
• Award a badge — should use cached inventory to find the badge item
• Verify cache resets after 6 hours or server restart

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