Make RHI usable for complex 3D scenarios

[kunitoki]

This pull request introduces major improvements and new features to the graphics rendering infrastructure, with a focus on GPU resource management, rendering performance, and new demo content. The changes include backend optimizations, expanded API capabilities, new demos, and documentation updates to reflect the latest features and fixes.

Graphics Backend and API Enhancements

• GpuTexture now caches backend texture views by view descriptor, reducing redundant allocations and improving performance, especially on Metal.
• GpuRenderPass now encodes all draws in a pass into a single backend render pass, avoiding expensive per-draw encoder creation and improving frame efficiency.
• GpuFrame no longer blocks on the GPU at scope end, reducing pipeline stalls and relying on backend-specific resource management. Frame numbers are now correctly reported to the ore context for better resource reclamation.
• Added GpuTexture::create() and upload() for direct texture allocation and pixel upload, supporting all backend formats and shapes. Added GpuSampler and GpuRenderPass::setSampler() for customizable sampling. [1] [2]
• GpuRenderPass now supports multiple color attachments, explicit depth/stencil, MSAA resolve, and expanded draw/viewport/scissor/blend operations. Bind groups are validated and errors are reported. [1] [2]

New Features and Demos

• Added a PBR IBL demo (physically based rendering with image-based lighting) and a Fluid Simulation demo (Navier-Stokes solver with GPU post-processing and bloom) to the graphics example app. [1] [2]

Performance and Synchronization Improvements

• Component effect paths now reuse offscreen GpuCanvas across frames for efficiency.
• New ComponentNative::vsync flag (with Options::withVSync()) synchronizes presentation to display refresh, improving pacing and avoiding timer conflicts.
• Fixed render loop hang when framerateRedraw is very high and improved timer precision on macOS.

Documentation Updates

• Updated documentation for new texture allocation and upload APIs, sampler usage, and expanded pass/draw operations. Clarified compute shader availability on WebGL2/Emscripten. [1] [2] [3]

Bug Fixes

• ShaderTranspiler now defaults to precision highp float; for GLSL ES fragment output, fixing math corruption on OpenGL ES.
• Fixed data races in KMeterState by making all relevant fields atomic and updating thread ownership.
• Various fixes for context/thread handling in SDL and GL, and improvements to resource cleanup and error reporting. [1] [2]

These changes significantly enhance the graphics subsystem's flexibility, performance, and reliability, while providing new demos and clearer documentation for advanced rendering features.

[codecov]

Codecov Report

❌ Patch coverage is 66.47887% with 238 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.50%. Comparing base (7bb7105) to head (e2bbbe3).

Files with missing lines	Patch %	Lines
modules/yup_rhi/rhi/yup_GpuRenderPass.cpp	58.82%	84 Missing ⚠️
modules/yup_rhi/rhi/yup_GpuPipeline.cpp	54.10%	67 Missing ⚠️
modules/yup_rhi/context/yup_GpuDevice.cpp	40.67%	35 Missing ⚠️
modules/yup_rhi/rhi/yup_GpuTexture.cpp	83.58%	22 Missing ⚠️
modules/yup_rhi/rhi/yup_ShaderBindingMap.cpp	40.00%	12 Missing ⚠️
modules/yup_rhi/rhi/yup_GpuTarget.cpp	77.77%	8 Missing ⚠️
modules/yup_rhi/rhi/yup_GpuSampler.cpp	83.33%	5 Missing ⚠️
modules/yup_rhi/context/yup_GpuDevice.h	0.00%	2 Missing ⚠️
modules/yup_rhi/rhi/yup_GpuSampler.h	33.33%	2 Missing ⚠️
modules/yup_rhi/rhi/yup_GpuFrame.cpp	97.14%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #181      +/-   ##
==========================================
- Coverage   81.60%   81.50%   -0.11%     
==========================================
  Files         796      798       +2     
  Lines       82713    83336     +623     
==========================================
+ Hits        67497    67920     +423     
- Misses      15216    15416     +200     

Files with missing lines	Coverage Δ
modules/yup_core/threads/yup_WaitableTimer.cpp	100.00% <100.00%> (+6.66%)	⬆️
modules/yup_gui/component/yup_ComponentNative.cpp	100.00% <100.00%> (ø)
modules/yup_gui/component/yup_ComponentNative.h	33.33% <ø> (ø)
modules/yup_rhi/rhi/yup_GpuFrame.h	50.00% <ø> (ø)
modules/yup_rhi/rhi/yup_GpuRenderPass.h	50.00% <ø> (ø)
modules/yup_rhi/rhi/yup_GpuTarget.h	75.00% <ø> (ø)
modules/yup_rhi/rhi/yup_GpuTexture.h	50.00% <ø> (ø)
modules/yup_rhi/rhi/yup_GpuTypes.h	100.00% <100.00%> (ø)
...dules/yup_shading/shading/yup_ShaderTranspiler.cpp	85.42% <100.00%> (+0.06%)	⬆️
modules/yup_rhi/rhi/yup_GpuFrame.cpp	96.25% <97.14%> (-0.18%)	⬇️
... and 9 more

... and 14 files with indirect coverage changes

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