Update tgfx to b8251c0d and adapt to new GPU API for instanced drawing support.

[domchen]

Summary

更新 tgfx 依赖到 b8251c0d 版本，适配新的 GPU API 变更：

• 将 VertexDescriptor(attributes) 改为 VertexBufferLayout 方式
• setVertexBuffer 添加 slot 参数
• draw 函数签名调整，参数顺序变化

Test plan

• 本地编译通过
• 193 个测试用例全部通过

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.15%. Comparing base (ea3d023) to head (7381968).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3222      +/-   ##
==========================================
- Coverage   77.16%   77.15%   -0.02%     
==========================================
  Files         413      413              
  Lines       21910    21910              
  Branches     6291     6292       +1     
==========================================
- Hits        16907    16904       -3     
- Misses       3804     3810       +6     
+ Partials     1199     1196       -3     

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[Copilot]

Pull request overview

This PR updates the tgfx dependency to commit b8251c0d and adapts the codebase to the new GPU API changes for instanced drawing support. The changes migrate from the old VertexDescriptor API to the new VertexBufferLayout API, and update function signatures for setVertexBuffer and draw methods.

Changes:

• Updated tgfx dependency commit hash in DEPS file
• Migrated from VertexDescriptor to VertexBufferLayout API for vertex attribute configuration
• Added slot parameter to setVertexBuffer calls for multi-buffer support
• Updated draw function calls to match new signature with removed base vertex offset parameter

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
DEPS	Updates tgfx dependency commit from 92250f90 to b8251c0d
src/rendering/filters/RuntimeFilter.cpp	Adapts to new tgfx GPU API: migrates to VertexBufferLayout, adds slot parameter to setVertexBuffer, and updates draw function signature

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