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>

.gitignore

@@ -10,3 +10,6 @@ dist
 
 # Secrets — never commit
 .gitea-token
+
+# VS Code user settings (workspace settings/.vscode/launch.json are committed)
+.vscode/settings.json