perf(view): Cache only latest screen-to-terrain result

[CryoTheRenegade]

Summary

In #2815 I profiled W3DView::m_locationRequests and found that only the newest entry was reused out of the 40 entry cache. The movement (moving camera in replays) test produced 33,590 newest-entry hits, while older cached entries had no hits.

This change replaces the 40 entry cache with a single entry cache that tracks bridge and seismic additions, deletions, and damage-state changes persistently so we can invalidate the entry when a change occurs.

[greptile-apps]

Greptile Summary

This PR changes screen-to-terrain caching to keep only the latest result. The main changes are:

• Replaces the old multi-entry location cache with a single cached screen/world pair.
• Adds view invalidation hooks for heightmap and bridge changes.
• Invalidates the cache from camera, terrain, seismic, and bridge update paths.
• Removes the now-unused position request typedefs.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp	Replaces the screen-to-terrain cache and adds invalidation for changed view state.
Core/GameEngineDevice/Include/W3DDevice/GameClient/W3DView.h	Stores the latest screen-to-terrain result and clears it when terrain or bridge state changes.
Core/GameEngineDevice/Source/W3DDevice/GameClient/BaseHeightMap.cpp	Routes full heightmap update scheduling through a helper that also invalidates the view cache.
Core/GameEngineDevice/Source/W3DDevice/GameClient/W3DTerrainVisual.cpp	Clears the view cache after seismic terrain updates.
Generals/Code/GameEngine/Source/GameLogic/Map/TerrainLogic.cpp	Clears the view cache when bridge logic adds, deletes, or updates bridge state.
GeneralsMD/Code/GameEngine/Source/GameLogic/Map/TerrainLogic.cpp	Mirrors the bridge cache invalidation changes for Zero Hour.

_{Reviews (3): Last reviewed commit: "refactor(view): Refine screen-to-terrain..." | Re-trigger Greptile}

[xezon]

Code looks complicated. Would be good to simplify it somehow.

[xezon]

Makes sense.