fix(config): 🔧 Add protocol prefixes to local API URLs

Updated MCP server configuration URLs to include `http://` protocol
prefix for:
- n8n API URL (`localhost:5678` → `http://localhost:5678`)
- Coolify base URL (`localhost:8000` → `http://localhost:8000`)
- Appwrite endpoint (`localhost:8088/v1` → `http://localhost:8088/v1`)

Also migrated logind configuration from `extraConfig` string to
structured
settings format for better maintainability.

```nix
services.logind.settings.Login = {
  RuntimeDirectorySize = "8G";
};

nixos/users.nix

@@ -18,5 +18,7 @@
   };
 
   # Change runtime directory size
-  services.logind.extraConfig = "RuntimeDirectorySize=8G";
+  services.logind.settings.Login = {
+    RuntimeDirectorySize="8G";
+  };
 }