refactor: 重构为多平台多用户架构，全面提升终端体验

- 新增 lib/ 辅助函数（mkNixos/mkDarwin/mkHome），消除硬编码
- 拆分 modules/ 为 nixos/darwin/shared 三层，支持跨平台共享
- 重构 home/ 为 shell/dev/theme 子模块，工具全部迁入用户级
- 深度配置 Tmux/FZF/Atuin/Bat/Eza/Btop/Lazygit/Starship
- 添加 Catppuccin Mocha 统一主题、Nerd Fonts 声明式管理
- 新增 homeConfigurations 输出，支持非 NixOS 系统直装
- 新增 nix-darwin 输入，预留 macOS 扩展路径
- 新增 overlays/ 和 pkgs/ 自定义包基础设施
- 修正 nix-darwin URL（LnL7 → nix-darwin org）

home/dev/default.nix

@@ -0,0 +1,7 @@
+{
+  imports = [
+    ./git.nix
+    ./languages.nix
+    ./neovim.nix
+  ];
+}

home/dev/git.nix

@@ -0,0 +1,59 @@
+{ ... }:
+
+{
+  programs.git = {
+    enable = true;
+
+    # user.name / user.email: set per-user via git config or ~/.zshrc.local
+    #   git config --global user.name "Your Name"
+    #   git config --global user.email "your@email.com"
+
+    delta = {
+      enable = true;
+      options = {
+        navigate = true;
+        side-by-side = true;
+        line-numbers = true;
+        hyperlinks = true;
+      };
+    };
+
+    extraConfig = {
+      # Internal Git server (skip SSL verification)
+      http."https://202.127.0.42:32443".sslVerify = false;
+
+      credential.helper = "store";
+      merge.conflictstyle = "zdiff3";
+      pull.rebase = true;
+      push.autoSetupRemote = true;
+      init.defaultBranch = "main";
+      rerere.enabled = true;
+      diff.algorithm = "histogram";
+      core.autocrlf = "input";
+    };
+  };
+
+  # ── Lazygit ──────────────────────────────────────────
+  programs.lazygit = {
+    enable = true;
+    settings = {
+      gui = {
+        nerdFontsVersion = "3";
+        showBottomLine = false;
+      };
+      git.paging = {
+        pager = "delta --paging=never";
+      };
+      update.method = "never";
+      disableStartupPopups = true;
+    };
+  };
+
+  # ── GitHub CLI ───────────────────────────────────────
+  programs.gh = {
+    enable = true;
+    settings = {
+      git_protocol = "ssh";
+    };
+  };
+}

home/dev/languages.nix

@@ -0,0 +1,41 @@
+{ pkgs, ... }:
+
+{
+  home.packages = with pkgs; [
+    # ── Language runtimes ──
+    nodejs
+    go
+    bun
+
+    # ── Package management / version management ──
+    mise
+    uv
+
+    # ── LSP servers ──
+    bash-language-server
+    gopls
+    typescript-language-server
+    yaml-language-server
+    vue-language-server
+    dockerfile-language-server-nodejs
+    lua-language-server
+    nil # Nix LSP
+
+    # ── Linter / Formatter ──
+    biome
+    ruff
+    shellcheck
+    shfmt
+    nixfmt-rfc-style # nix formatter
+    stylua
+
+    # ── Code intelligence ──
+    ast-grep
+  ];
+
+  # ── mise config ──────────────────────────────────────
+  xdg.configFile."mise/config.toml".text = ''
+    [settings]
+    trusted_config_paths = ["/"]
+  '';
+}

home/dev/neovim.nix

@@ -0,0 +1,24 @@
+{ pkgs, ... }:
+
+{
+  programs.neovim = {
+    enable = true;
+    defaultEditor = true;
+    viAlias = true;
+    vimAlias = true;
+    withNodeJs = true;
+    withPython3 = true;
+  };
+
+  # ── Neovim distro configuration ──
+  # Option A: LazyVim / NvChad / AstroNvim via xdg.configFile
+  #   xdg.configFile."nvim" = {
+  #     source = ./nvim-config;
+  #     recursive = true;
+  #   };
+  #
+  # Option B: NixVim (fully declarative)
+  #   Add to flake.nix inputs:
+  #     nixvim.url = "github:nix-community/nixvim";
+  #   Then configure here.
+}