refactor: KISS cleanup — deduplicate shared config, merge thin files

- Extract fonts, fish.enable, openssh.enable to modules/shared/
- Centralize sshKeys in lib/ via specialArgs
- Merge nixos/base.nix + locale.nix into nixos/default.nix
- Merge home/theme.nix into home/default.nix
- Simplify homeManagerConfig, flake packages output
- Remove redundant vim/wget from NixOS system packages
- Update AGENTS.md to reflect new structure

modules/nixos/docker.nix

@@ -8,8 +8,4 @@
   environment.systemPackages = with pkgs; [
     docker-compose
   ];
-
-  # WSL 环境下如使用 Docker Desktop，可改为：
-  #   wsl.docker-desktop.enable = true;
-  # 并将上面的 virtualisation.docker.enable 设为 false
 }