PHLEGM v5 generated graphics shaders

Display GLSL/HLSL files are compiled from cfg/filters/classic.filters.phlegm.
Build-PHLEGM-v5.ps1 invokes scripts/Compile-PHLEGM-Shaders.ps1 before each
FreeBASIC target. OpenGL consumes generated GLSL source; D3D11 builds also
compile generated HLSL to Shader Model 5 .cso bytecode using Windows
d3dcompiler_47.dll. Generated sources are retained for inspection/reproducibility.

The shader tree also carries cheat-search compute kernels:
- OpenGL: cheat-search.comp.glsl (GLSL compute)
- D3D11: cheat-search.cs.hlsl (compiled as cs_5_0 on Windows builds)

These kernels define PHLEGM's backend-neutral bulk cheat-search contract. The
current emulator core uses its CPU search fallback until the presentation backend
exposes generic compute-buffer dispatch/readback. Cheat application/freeze writes
remain CPU-side through BusWrite by design.
