refactor(build): 切换到 musl 交叉编译 + distroless 镜像方案

- docker-publish.yml: 改为 cross 交叉编译 amd64/arm64 musl 静态二进制,
  前端在 CI 独立构建, buildx 组装多架构镜像
- Dockerfile.app: 从 139 行容器内编译简化为 24 行纯 COPY 打包
- Dockerfile.app.local: 移除 jemalloc 动态链接 (LD_PRELOAD/libjemalloc2)
- aether-gateway: 引入 tikv-jemallocator 静态链接 jemalloc

apps/aether-gateway/src/main.rs

@@ -1,3 +1,7 @@
+#[cfg(not(target_env = "msvc"))]
+#[global_allocator]
+static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
+
 use clap::{Args as ClapArgs, Parser, ValueEnum};
 use tracing::{debug, info, warn};