* Add s2h example
* Add s2h Hello Screen example
* Add gather feature example
* Add Arrow, Coordinate System and Table S2H examples
* Add generate user font s2h example
* Add 2D s2h example
* Add 3D s2h example
* Add clear s2h example
* Add Quad Post s2h example
* Add Use User Font s2h example
* Add Debug Zoom s2h example
* Add Quad VS/PS s2h example
* Add Scatter s2h example
* Update s2h_scatter.hlsl (more readable)
* Add Zoom 2D s2h example
* Update s2h samples order to corespong to GiGi one
Enhance Gather sample to looks more like the original one
* Handle bottom-left fragment origins in S2H shaders
* Fix S2H rendering across OpenGL, Vulkan, and DX12
* Removed the redundant u_s2hScreen uniform
- S2H now derives the top-left pixel coordinate from bgfx’s u_viewRect and OpenGL’s built-in bgfx_ndc.z
- Removed its creation, per-view uploads, and destruction from s2h.cpp
* Update 54-s2h shaders to match bgfx shader style
`float2/3/4` → `vec2/3/4`
`float4x4` → `mat4`
`int2 / uint2` → `ivec2 / uvec2`
