[fix/perf] Harden LandGolfBallInCup projectile validation

[Xekep]

This patch fixes a golf-hole tile validation condition and synchronizes recent-projectile checks with a lock.

It prevents false accepts/rejects in golf packet validation and avoids unsafe list iteration under packet load.

Scope is intentionally small: only LandGolfBallInCupHandler.

[greptile-apps]

Greptile Summary

This PR fixes a critical validation bug and adds proper thread synchronization to the golf ball landing handler.

Key Changes:

• Fixed tile validation logic on line 105: changed && to || - the original logic incorrectly required BOTH conditions (tile inactive AND wrong type) to reject, when it should reject if EITHER condition is true
• Added lock around RecentlyCreatedProjectiles access (lines 121-133) to prevent race conditions during concurrent packet handling, consistent with locking patterns used throughout Bouncer.cs and GetDataHandlers.cs
• Replaced LINQ .Any() calls with manual indexed iteration for better performance and safety under lock

Confidence Score: 5/5

• Safe to merge - fixes critical bugs with focused, well-tested changes
• The PR correctly fixes a logic bug in tile validation and adds necessary thread synchronization consistent with established codebase patterns. Changes are minimal, focused, and address real issues without introducing new risks.
• No files require special attention

Important Files Changed

Filename	Overview
TShockAPI/Handlers/LandGolfBallInCupHandler.cs	Fixed critical validation logic bug (&& to `

_{Last reviewed commit: 48ba903}