fix: 添加cargo清华镜像源，加速Hub本地构建

aether-hub/Dockerfile

@@ -3,6 +3,13 @@
 FROM rust:1.85-slim AS builder
 WORKDIR /build/aether-hub
 
+# 可选：配置国内 Cargo 镜像源（本地构建时传 --build-arg CARGO_MIRROR=1）
+ARG CARGO_MIRROR
+RUN if [ -n "$CARGO_MIRROR" ]; then \
+    printf '[source.crates-io]\nreplace-with = "tuna"\n\n[source.tuna]\nregistry = "sparse+https://mirrors.tuna.tsinghua.edu.cn/crates.io-index/"\n' \
+    > /usr/local/cargo/config.toml; \
+    fi
+
 # 先构建依赖层，最大化后续代码变更时的缓存命中
 COPY Cargo.toml Cargo.lock ./
 RUN mkdir src && printf 'fn main() {}\n' > src/main.rs