Update deployment guide and krops configuration for improved clarity and consistency

Enhanced the DEPLOYMENT-GUIDE.md by adding clarity to the steps for adding new machines, updating environment variables, images, and web-app code. Adjusted formatting for better readability. In krops.nix, updated the target hostname for machine1 to 'root@cathare-node' and changed the Nixpkgs reference from 'nixos-25.05' to '25.05' for consistency. These changes improve the documentation and configuration management for the deployment process.

DEPLOYMENT-GUIDE.md

@@ -3,6 +3,7 @@
 ## Overview
 
 This setup builds the web-app **locally** with machine-specific configuration, then deploys the built artifacts to each target machine. Each machine gets its own customized build with:
+
 - Machine-specific `.env` files
 - Machine-specific images in the `public` folder
 
@@ -47,6 +48,7 @@ nix-build ./build-local.nix -A all && ./result/bin/build-all
 ```
 
 This:
+
 1. Copies web-app source to `./build/{machine}/`
 2. Copies machine-specific `.env` file
 3. Copies machine-specific images to `public/`
@@ -79,19 +81,24 @@ nix-build ./krops.nix -A all && ./result
 
 ## Customization
 
-### Add a new machine:
+### Add a new machine
+
 1. Create directories: `machine-specific/machine3/env/` and `machine-specific/machine3/images/`
 2. Add `.env` file and images for machine3
 3. Create `config/machine3/configuration.nix`
 4. Add machine3 to `build-local.nix` and `krops.nix`
 
-### Update environment variables:
+### Update environment variables
+
 Edit `.env` in `machine-specific/{machine-name}/env/.env`, then rebuild locally
 
-### Update images:
+### Update images
+
 Replace files in `machine-specific/{machine-name}/images/`, then rebuild locally
 
-### Update web-app code:
+### Update web-app code
+
 Edit files in `web-app/`, then rebuild locally
 
-After any changes: rebuild locally, then redeploy.
+After any changes: rebuild locally, then redeploy.
+