refactor: use michaotic username throughout, add cli/kitty/zsh configs and docs

docs/structure.md

@@ -0,0 +1,63 @@
+# structure
+
+how the config is organized.
+
+## top-level
+
+```
+nix-config/
+├── flake.nix          # entry point - dispatches to hosts
+├── home/              # home-manager (user space)
+├── hosts/             # system-level configs
+├── secrets/           # sops-nix encrypted files
+└── docs/              # this folder
+```
+
+## flake.nix flow
+
+```
+flake.nix
+├── nixosConfigurations
+│   ├── muscari  → hosts/muscari/ + home/
+│   └── rosemary → hosts/rosemary/ + home/
+└── darwinConfigurations
+    └── poppy    → hosts/poppy/ + home/
+```
+
+## home/ vs hosts/
+
+| what | where | why |
+|------|-------|-----|
+| shell config | `home/` | same on all machines |
+| terminal emulator | `home/` | gui apps belong here |
+| system packages | `hosts/<name>/` | os-specific |
+| networking | `hosts/<name>/` | per-host |
+| hostname | `hosts/<name>/` | obviously |
+
+## adding things
+
+**new package for all hosts:**
+→ add to `home/cli.nix` in `home.packages`
+
+**new package for one host:**
+→ add to `hosts/<name>/default.nix` in `environment.systemPackages`
+
+**new alias for all hosts:**
+→ add to `home/zsh.nix` in `programs.zsh.shellAliases`
+
+**new alias for one host:**
+→ add to `hosts/<name>/default.nix` in `home-manager.users.mikl.programs.zsh.shellAliases`
+
+## host-specific imports
+
+poppy imports `home/kitty.nix` because it has a screen. muscari doesn't.
+
+```nix
+# hosts/poppy/default.nix
+home-manager.users.mikl = {
+  imports = [ ../../home/kitty.nix ];
+  programs.zsh.shellAliases = {
+    switch = "darwin-rebuild switch --flake .#poppy";
+  };
+};
+```