Add Emacs desktop provisioning and dev toolchain packages

Install Emacs and copy the desktop .emacs.d config so the editor setup is managed with the rest of desktop dotfiles. Add vterm/build/debug dependencies plus C/C++ and Go tooling needed by the configured workflow.

dotfiles/desktop/.emacs.d/snippets/yaml-mode/k8ingress

@@ -0,0 +1,18 @@
+#key : k8s/ingress
+# --
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: ${1:foo}-ingress
+spec:
+  rules:
+    - host: $1.`system-name`
+      http:
+        paths:
+          - pathType: Prefix
+            path: /
+            backend:
+              service:
+                port:
+                  number: 80
+                name: colour-service