feat: add Copilot instructions and guidelines for unit tests and release notes

.vscode/settings.json

@@ -0,0 +1,15 @@
+{
+  "github.copilot.chat.reviewSelection.instructions": [
+    {
+      "text": "Review the code changes carefully before accepting them."
+    }
+  ],
+  "github.copilot.chat.commitMessageGeneration.instructions": [
+    {
+      "text": "Use conventional commit message format."
+    }
+  ],
+  "github.copilot.chat.pullRequestDescriptionGeneration.instructions": [
+    { "text": "Always include a list of key changes." }
+  ]
+}