Add AMD GPU support for Smooth 60 fps via AMF FRC

[RahnRazamai]

Title

Add AMD GPU support for Smooth 60 fps via AMF FRC

Summary

Add an AMD backend for Smooth 60 fps using AMD Advanced Media Framework Frame Rate Conversion.

Motivation

Smooth 60 fps currently depends on NVIDIA Optical Flow / FRUC. AMD AMF includes a Video FRC component that can generate interpolated frames and should map to the existing frame interpolation concept.

Proposed Scope

• Add optional AMD AMF FRC backend for frame interpolation.
• Keep existing NVIDIA FRUC path unchanged.
• Capability probing should enable Smooth 60 fps if either NVIDIA FRUC or AMD AMF FRC is available.
• Reuse the current capture loop behavior: real camera frame plus interpolated midpoint frame.
• Add build flags/env vars for AMF, e.g. COS_AMF_SDK_DIR and COS_HAS_AMF_FRC.

Out of Scope

• AMD Eye Contact.
• Green Screen / DirectML segmentation.
• Replacing NVIDIA FRUC.
• Driver-level AFMF integration.

Implementation Notes

Likely files:

• native/shim/fruc.*
• new native/shim/amd_frc.*
• native/shim/capture.*
• native/shim/shim.*
• native/shim/shim.vcxproj
• bundle / installer scripts if redistributing AMF runtime files
• README / THIRD-PARTY-NOTICES

Acceptance Criteria

• On NVIDIA RTX, existing FRUC still works.
• On AMD GPU with AMF FRC available, Smooth 60 fps toggle enables.
• On unsupported machines, Smooth 60 fps remains disabled with a clear reason.
• Stub/no-SDK builds still compile.
• Core tests cover capability gating.
• A manual AMD verification checklist is added.