feat: Add little-rascal laptop config and lab-tool auto-update system

## New Machine: little-rascal
- Add Lenovo Yoga Slim 7 14ARE05 configuration (AMD Ryzen 7 4700U)
- Niri desktop with CLI login (greetd + tuigreet)
- zram swap configuration (25% of RAM with zstd)
- AMD-optimized hardware support and power management
- Based on congenital-optimist structure with laptop-specific additions

## Lab Tool Auto-Update System
- Implement Guile Scheme auto-update module (lab/auto-update.scm)
- Add health checks, logging, and safety features
- Integrate with existing deployment and machine management
- Update main CLI with auto-update and auto-update-status commands
- Create NixOS service module for automated updates
- Document complete implementation in simple-auto-update-plan.md

## MCP Integration
- Configure Task Master AI and Context7 MCP servers
- Set up local Ollama integration for AI processing
- Add proper environment configuration for existing models

## Infrastructure Updates
- Add little-rascal to flake.nix with deploy-rs support
- Fix common user configuration issues
- Create missing emacs.nix module
- Update package integrations

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

flake.nix

@@ -76,6 +76,18 @@
           ./modules/common/tty.nix
         ];
       };
+
+      # little-rascal - Development laptop with Niri + CLI login
+      little-rascal = nixpkgs.lib.nixosSystem {
+        inherit system specialArgs;
+        modules = [
+          ./machines/little-rascal/configuration.nix
+          ./machines/little-rascal/hardware-configuration.nix
+          ./modules/common/nix.nix
+          ./modules/common/base.nix
+          ./modules/common/tty.nix
+        ];
+      };
     };
 
     # Custom packages for the home lab
@@ -100,6 +112,7 @@
           echo "  - sleeper-service (Xeon file server)"
           echo "  - reverse-proxy (VPS edge server)"
           echo "  - grey-area (Services host: Forgejo, Jellyfin, etc.)"
+          echo "  - little-rascal (Development laptop with Niri)"
           echo ""
           echo "Build with: nixos-rebuild build --flake .#<config>"
           echo "Switch with: nixos-rebuild switch --flake .#<config>"
@@ -205,6 +218,20 @@
           confirmTimeout = 30;
         };
       };
+
+      little-rascal = {
+        hostname = "little-rascal.tail807ea.ts.net";
+        profiles.system = {
+          user = "root";
+          path = deploy-rs.lib.x86_64-linux.activate.nixos self.nixosConfigurations.little-rascal;
+          sshUser = "geir";
+          sudo = "sudo -u";
+          autoRollback = true;
+          magicRollback = true;
+          activationTimeout = 180;
+          confirmTimeout = 30;
+        };
+      };
     };
 
     # Deploy-rs checks (recommended by deploy-rs)