Conflict resolutions:

ContentDecoder.cpp — HW decode init restructured to accommodate all three
platforms under one unified block. Upstream added Windows D3D11VA support
(e-dream-ai#584/e-dream-ai#598) using #if USE_HW_ACCELERATION + #if WIN32. Our Linux VAAPI
block moved to an #elif LINUX_GNU since USE_HW_ACCELERATION=0 on Linux.
Mac VideoToolbox kept in the #else branch with our improved error handling
(av_buffer_ref, get_format, proper fallback logging).

Clip.cpp (constructor) — upstream adds m_spDecoder->SetD3D11Device() in
a #ifdef WIN32 block for D3D11VA frame sharing; our #ifdef LINUX_GNU frame
generation init retained below it. Both kept.

Clip.cpp (GrabVideoFrame) — upstream inlined the frame upload logic; we
kept our UploadFrameToTexture() call which handles D3D11VA HW frames,
RGB24 (RIFE path), and RGBA. Updated UploadFrameToTexture to also detect
isHWFrame for correct Windows D3D11VA BindFrame routing.

client.h (F1 help text) — added upstream's settings shortcut
(FULLSCREEN_MODIFIER_KEY-comma) using our BK() macro style.

client.h (GPU display) — kept our m_RuntimeDiagnostics.gpuFrameTimeMs
(already sourced from GetGPUFrameTimeMs()) but adopted upstream's
", %i%% app" label for the system GPU utilization string.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>