refactor: gate ssh sops symlinks, follow nixos-wsl, fix CRLF

- home/ssh.nix: only create /run/secrets symlinks when secrets exist
- flake.nix: nixos-wsl explicit nixpkgs follows
- fix CRLF line endings: nvchad.nix, virtualbox-guest.nix, docker.nix

home/nvchad.nix

@@ -1,28 +1,28 @@
-{ config, pkgs, inputs, system, ... }:
-{
-  # 导入 NvChad 模块
-  imports = [
-    inputs.nix4nvchad.homeManagerModules.default
-  ];
-
-  programs.nvchad = {
-    enable = true;
-
-    # NvChad 需要的额外包
-    extraPackages = with pkgs; [
-      # LSP 服务器
-      nil                # Nix LSP
-      marksman           # Markdown LSP
-
-      # 格式化工具
-      nixpkgs-fmt
-      shfmt
-    ];
-  };
-
-  # 设置默认编辑器
-  home.sessionVariables = {
-    EDITOR = "nvim";
-    VISUAL = "nvim";
-  };
-}
+{ config, pkgs, inputs, system, ... }:
+{
+  # 导入 NvChad 模块
+  imports = [
+    inputs.nix4nvchad.homeManagerModules.default
+  ];
+
+  programs.nvchad = {
+    enable = true;
+
+    # NvChad 需要的额外包
+    extraPackages = with pkgs; [
+      # LSP 服务器
+      nil                # Nix LSP
+      marksman           # Markdown LSP
+
+      # 格式化工具
+      nixpkgs-fmt
+      shfmt
+    ];
+  };
+
+  # 设置默认编辑器
+  home.sessionVariables = {
+    EDITOR = "nvim";
+    VISUAL = "nvim";
+  };
+}