Add VS Code workspace settings

- Configure auto-approve for git commit in chat tools
- Set default solution file

.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+    "chat.tools.terminal.autoApprove": {
+        "git commit": true
+    },
+    "dotnet.defaultSolution": "ASTRAIN.slnx"
+}