Add Image Deform/Liquify feature to iOS demo, aligning with Android version

[Copilot]

Adds the interactive image deformation (liquify) feature to iOS, matching the Android version's ImageDeformActivity. The iOS library already had the C++ CGELiquidationFilter implementation but lacked the Objective-C wrapper and demo UI.

Changes

Library

• CGEDeformFilterWrapper (cge/interfaces/) - Objective-C wrapper for CGELiquidationFilter
  • Forward, bloat, wrinkle, restore deformation modes
  • Undo/redo with configurable step limit
  • Mesh visualization toggle
  • Input validation on creation
• Updated cge.h umbrella headers to export the new wrapper

Demo

• ImageDeformViewController - Touch-based deformation demo
  • Pan gesture for real-time mesh manipulation
  • Mode selection (Forward/Bloat/Wrinkle/Restore)
  • Adjustable radius and intensity
  • Gallery integration and save functionality
• Added "Image Deform Demo" entry to Main.storyboard

Documentation

• Updated README with feature list and usage example

Usage

#import "cgeDeformFilterWrapper.h"

CGEDeformFilterWrapper* wrapper = [CGEDeformFilterWrapper createWithWidth:1280 
                                                                   height:720 
                                                                   stride:10.0f];
[wrapper setUndoSteps:50];

// Forward deform (push pixels)
[wrapper forwardDeformWithStartX:100 startY:100 endX:150 endY:150 
                           width:canvasWidth height:canvasHeight 
                          radius:100.0f intensity:0.15f];

// Undo/redo
if ([wrapper canUndo]) [wrapper undo];

Manual Step Required

Add new files to Xcode projects:

• cgeDeformFilterWrapper.h/mm → cgeFramework.xcodeproj
• ImageDeformViewController.h/mm → cgeDemo.xcodeproj

Original prompt

任务: 帮我迭代这个项目， 对齐安卓版本 https://github.com/wysaid/android-gpuimage-plus/ 的液化功能。 描述：本项目有一段时间没有迭代了， 功能已经落后了安卓版本较多。 请审查本项目与安卓版本项目的差异， 帮我补全功能（尤其是 Demo 展示这块） 目前安卓版已经有一个单独的页面用于展示液化相关的功能。 重点关注一下这个功能。 开发完毕之后， 也顺便更新一下项目的描述

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