fix: restore workshop WiFi connection setup service

- Add back the missing workshop-wifi-setup systemd service
- Service creates and connects to 'ziegel' WiFi network automatically
- Fixes missing WiFi connection that was present in main branch
- Provides fallback hotspot connectivity for workshop environment

common.nix

@@ -265,6 +265,44 @@ isoConfig
     mode = "0600";
   };
 
+  # WiFi connection setup service
+  systemd.services.workshop-wifi-setup = {
+    description = "Set up workshop WiFi connection";
+    wantedBy = [ "multi-user.target" ];
+    after = [ "NetworkManager.service" ];
+    wants = [ "NetworkManager.service" ];
+    path = with pkgs; [
+      networkmanager
+      coreutils
+      gnugrep
+    ];
+    script = ''
+      # Source credentials
+      source /etc/NetworkManager/workshop-wifi.env
+
+      # Check if connection already exists
+      if nmcli connection show | grep -q "ziegel"; then
+        echo "✅ Workshop WiFi connection already exists"
+        exit 0
+      fi
+
+      echo "📡 Setting up workshop WiFi connection..."
+      # Create WiFi connection
+      if nmcli device wifi connect "$WORKSHOP_SSID" password "$WORKSHOP_PSK" hidden no; then
+        echo "✅ Workshop WiFi connection created and connected"
+      else
+        echo "⚠️ Could not connect to workshop WiFi (network may not be available)"
+        echo "   SSID: $WORKSHOP_SSID"
+        echo "   Manual connection: nmcli device wifi connect '$WORKSHOP_SSID' password '$WORKSHOP_PSK'"
+      fi
+    '';
+    serviceConfig = {
+      Type = "oneshot";
+      User = "root";
+      RemainAfterExit = true;
+    };
+  };
+
   # DNS Configuration - Wildcard *.workshop.local -> 127.0.0.1
   services.dnsmasq = {
     enable = true;