Fix L85: move launch.json from .claude/ to .vscode/ where VS Code reads it

.claude/launch.json was committed but VS Code reads launch configs from
.vscode/launch.json, so no tool was consuming it. Moved to the correct
location and removed the misplaced file from git tracking.

Also added .vscode/settings.json to .gitignore so local VS Code user
preferences don't end up tracked.

typecheck + 242 tests green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.vscode/launch.json

@@ -0,0 +1,11 @@
+{
+  "version": "0.0.1",
+  "configurations": [
+    {
+      "name": "ui",
+      "runtimeExecutable": "npm",
+      "runtimeArgs": ["run", "ui"],
+      "port": 5174
+    }
+  ]
+}