feat: 添加 Linux ARM64 平台支持

## 新增功能

添加 Linux ARM64 (aarch64) 平台的构建支持，满足树莓派、ARM 服务器等设备需求。

## 技术实现

### 1. 构建矩阵扩展
- 添加 `aarch64-unknown-linux-gnu` target
- 使用 Ubuntu 22.04 进行交叉编译

### 2. 交叉编译工具链
- 安装 `gcc-aarch64-linux-gnu` 和 `g++-aarch64-linux-gnu`
- 配置 ARM64 系统库：
  - libwebkit2gtk-4.1-dev:arm64
  - libappindicator3-dev:arm64
  - librsvg2-dev:arm64
  - libssl-dev:arm64
  - libgtk-3-dev:arm64

### 3. 环境配置
- `PKG_CONFIG_ALLOW_CROSS=1`: 允许交叉编译
- `PKG_CONFIG_PATH`: 指向 ARM64 库路径
- `CARGO_TARGET_*_LINKER`: 配置链接器
- `CC_*` / `CXX_*`: 配置 C/C++ 编译器

## 发布产物

新增以下文件：
- `proxycast_*_arm64.deb` - Debian/Ubuntu ARM64 安装包
- `proxycast_*_arm64.AppImage` - 通用 Linux ARM64 可执行文件

## 支持设备

- 树莓派 (Raspberry Pi 3/4/5)
- ARM 服务器 (AWS Graviton, 华为鲲鹏等)
- ARM 笔记本 (如 ARM Chromebook)
- Apple Silicon Mac 运行 Linux (通过虚拟机或双系统)

## 测试建议

发布后建议在以下设备测试：
1. 树莓派 4 (Raspberry Pi OS)
2. Ubuntu 22.04 ARM64 虚拟机
3. AWS Graviton 实例

Closes #54

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/release.yml

@@ -32,6 +32,9 @@ jobs:
           - platform: ubuntu-22.04
             target: x86_64-unknown-linux-gnu
             name: Linux-x64
+          - platform: ubuntu-22.04
+            target: aarch64-unknown-linux-gnu
+            name: Linux-arm64
 
     runs-on: ${{ matrix.platform }}
     
@@ -45,12 +48,39 @@ jobs:
           node-version: '20'
           cache: 'npm'
 
-      - name: Install Linux dependencies
-        if: matrix.platform == 'ubuntu-22.04'
+      - name: Install Linux dependencies (x64)
+        if: matrix.platform == 'ubuntu-22.04' && matrix.target == 'x86_64-unknown-linux-gnu'
         run: |
           sudo apt-get update
           sudo apt-get install -y libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev patchelf
 
+      - name: Install Linux ARM64 cross-compilation dependencies
+        if: matrix.platform == 'ubuntu-22.04' && matrix.target == 'aarch64-unknown-linux-gnu'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y gcc-aarch64-linux-gnu g++-aarch64-linux-gnu
+
+          # 添加 ARM64 架构支持
+          sudo dpkg --add-architecture arm64
+          sudo apt-get update
+
+          # 安装 ARM64 系统库
+          sudo apt-get install -y \
+            libwebkit2gtk-4.1-dev:arm64 \
+            libappindicator3-dev:arm64 \
+            librsvg2-dev:arm64 \
+            libssl-dev:arm64 \
+            libgtk-3-dev:arm64
+
+          # 设置 PKG_CONFIG 环境变量
+          echo "PKG_CONFIG_ALLOW_CROSS=1" >> $GITHUB_ENV
+          echo "PKG_CONFIG_PATH=/usr/lib/aarch64-linux-gnu/pkgconfig" >> $GITHUB_ENV
+
+          # 设置 Cargo 环境变量
+          echo "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=aarch64-linux-gnu-gcc" >> $GITHUB_ENV
+          echo "CC_aarch64_unknown_linux_gnu=aarch64-linux-gnu-gcc" >> $GITHUB_ENV
+          echo "CXX_aarch64_unknown_linux_gnu=aarch64-linux-gnu-g++" >> $GITHUB_ENV
+
       - name: Setup Rust
         uses: dtolnay/rust-toolchain@stable
         with:
@@ -87,7 +117,8 @@ jobs:
             - **macOS (Apple Silicon)**: `proxycast_*_aarch64.dmg`
             - **macOS (Intel)**: `proxycast_*_x64.dmg`
             - **Windows (64-bit)**: `proxycast_*_x64-setup.exe`
-            - **Linux (64-bit)**: `proxycast_*_amd64.deb` / `proxycast_*_amd64.AppImage`
+            - **Linux x64**: `proxycast_*_amd64.deb` / `proxycast_*_amd64.AppImage`
+            - **Linux ARM64**: `proxycast_*_arm64.deb` / `proxycast_*_arm64.AppImage`
             
             ### macOS 首次安装