UI post-processing basic code

[GengineJS]

No description provided.

[github-actions]

Code Size Check Report

Wechat (WASM)	Before	After	Diff
2D Empty (legacy pipeline)	1005977 bytes	1005977 bytes	✅ 0 bytes
2D All (legacy pipeline)	2671067 bytes	2671067 bytes	✅ 0 bytes
2D All (new pipeline)	2761184 bytes	2761184 bytes	✅ 0 bytes
(2D + 3D) All	10017488 bytes	10017488 bytes	✅ 0 bytes

Web (WASM + ASMJS)	Before	After	Diff
(2D + 3D) All	16839109 bytes	16839109 bytes	✅ 0 bytes

Interface Check Report

This pull request does not change any public interfaces !