chore(devcontainer): add markdown-mermaid extension (#3986)

* feat(devcontainer): add markdown-mermaid extension for enhanced diagram support

* Add valid commit scopes to settings

---------

Co-authored-by: Frida Erdal <31915755+pomfrida@users.noreply.github.com>
Co-authored-by: Frida <fridaerdal@hotmail.no>

Author: Hjaf

.devcontainer/devcontainer.json

@@ -54,6 +54,7 @@
         "jock.svg",
         "github.vscode-pull-request-github",
         "ms-azuretools.vscode-bicep",
+        "bierner.markdown-mermaid",
         "bierner.github-markdown-preview"
       ]
     }

.vscode/settings.json

@@ -33,7 +33,10 @@
     "design-system-docs",
     "github",
     "config",
-    "eds-demo"
+    "eds-demo",
+    "devcontainer",
+    "build",
+    "deps"
   ],
   "cSpell.words": [
     "APCA",