重构项目结构：扁平化配置并支持 curl 一键安装

- 将 arch-config/ 内容移至仓库根目录
- setup.sh 重命名为 install.sh
- 脚本改为自动 clone 仓库到 ~/.config/arch-config
- 新增 pacman -Syu 系统更新步骤
- README 简化为 curl 一行安装

files/etc/pacman.d/mirrorlist

@@ -0,0 +1,2 @@
+Server = https://mirrors.tuna.tsinghua.edu.cn/archlinux/$repo/os/$arch
+Server = https://mirrors.ustc.edu.cn/archlinux/$repo/os/$arch

files/home/.zshrc

@@ -0,0 +1,20 @@
+# Oh My Zsh
+export ZSH="$HOME/.oh-my-zsh"
+ZSH_THEME="robbyrussell"
+plugins=(git zsh-autosuggestions zsh-syntax-highlighting)
+source $ZSH/oh-my-zsh.sh
+
+# mise
+if command -v mise &> /dev/null; then
+    eval "$(mise activate zsh)"
+fi
+
+# zoxide
+if command -v zoxide &> /dev/null; then
+    eval "$(zoxide init zsh)"
+fi
+
+# Aliases
+alias ls='ls --color=auto'
+alias ll='ls -lah'
+alias cd='z'