Add treefmt

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

README.md

@@ -7,6 +7,7 @@ NixOS dotfiles and configuration for various hosts and users.
 - [`flake.lock`](./flake.lock) and [`flake.nix`](./flake.nix): Core Nix flake files defining the repository's dependencies and entry points.
 
 - [`hosts/`](./hosts): All host-specific configurations.
+
   - [`common/`](./hosts/common): Shared configuration definitions.
     - [`shells/`](./hosts/common/shells): Nix dev shells.
     - [`configs/`](./hosts/common/configs): System configurations applicable to all hosts.
@@ -19,6 +20,7 @@ NixOS dotfiles and configuration for various hosts and users.
 - `secrets/<namespace>/`: Global secrets for individual namespaces that apply across all hosts.
 
 - [`lib/`](./lib): Nix library function definitions and utilities.
+
   - [`scripts/`](./lib/scripts): Utility scripts for managing the repository.
     - [`add-host.sh`](./lib/scripts/add-host.sh): Instantiate the keys for a new host configuration.
     - [`remove-host.sh`](./lib/scripts/remove-host.sh): Remove references to a host.
@@ -34,7 +36,7 @@ Any `options.nix` files create custom option definitions when present.
 Below is a table of all hosts, with links to their respective README files, which may provide further details and/or post-installation checklists.
 
 | Host        | README                                                   |
-|-------------|----------------------------------------------------------|
+| ----------- | -------------------------------------------------------- |
 | `installer` | [hosts/installer/README.md](./hosts/installer/README.md) |
 | `eirene`    | [hosts/eirene/README.md](./hosts/eirene/README.md)       |
 | `elara`     | [hosts/elara/README.md](./hosts/elara/README.md)         |