Do not automatically install arcade-skills plugins (#54136)

Author: lbussell

.claude/settings.json

@@ -1,13 +1,19 @@
 {
   "extraKnownMarketplaces": {
+    "dotnet-skills": {
+      "source": {
+        "source": "github",
+        "repo": "dotnet/skills"
+      }
+    },
     "dotnet-arcade-skills": {
       "source": {
         "source": "github",
         "repo": "dotnet/arcade-skills"
       }
     }
   },
-  "enabledPlugins": {
-    "dotnet-dnceng@dotnet-arcade-skills": true
-  }
+  "companyAnnouncements": [
+    "Run `/plugin install dotnet-dnceng@dotnet-arcade-skills` to install useful plugins for investigating Helix and Azure Pipelines runs."
+  ]
 }

.github/copilot/settings.json

@@ -52,5 +52,12 @@ cmake/
 # Live Unit Testing
 *.lutconfig
 
-# Claude code config files
+###############################################################################
+# Coding agents
+###############################################################################
+
+# Claude Code user-local settings
 .claude/settings.local.json
+# GitHub Copilot CLI user-local settings
+# See https://docs.github.com/copilot/reference/copilot-cli-reference/cli-config-dir-reference#configuration-file-settings
+.github/copilot/settings.local.json