Investigate hardcoded offset for enableWaterTAA in BSImagespaceShaderISTemporalAA

Description

The code currently uses a hardcoded memory offset (0x38LL) to access the enableWaterTAA member in the BSImagespaceShaderISTemporalAA structure:

bool* enableWaterTAA = reinterpret_cast<bool*>(reinterpret_cast<uintptr_t>(BSImagespaceShaderISTemporalAA) + 0x38LL);

Location: src/Features/Upscaling.cpp:705

Tasks

• Investigate if CommonLibSSE/CommonLibVR has already reverse engineered the BSImagespaceShaderISTemporalAA structure. We use the ng branch of commonlibvr.
• If available in CommonLib, refactor to use the proper structure member instead of hardcoded offset
• If not available, perform RE work to properly define the structure
• Document the structure definition for maintainability

Context

Hardcoded offsets are fragile and can break with game updates or across different game versions. Using proper structure definitions from CommonLib (if available) or creating our own RE definitions would make this code more maintainable.

References

• PR: https://github.com/doodlum/skyrim-community-shaders/pull/1726
• Comment: https://github.com/doodlum/skyrim-community-shaders/pull/1726#discussion_r2700756452
• Requested by: @alandtse