chore: update .gitignore to exclude temp screenshots and build artifacts

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -25,9 +25,19 @@ desktop/src-tauri/gen/
 # Desktop brand asset candidates (keep only selected ones in public/)
 desktop/brand-assets/
 
-# Claude worktrees
+# Claude worktrees & auto-generated
 .claude/worktrees/
 .claude/scheduled_tasks.lock
+.claude/scheduled_tasks.json
+
+# Debug / temp screenshots (root dir only)
+/*.png
+
+# TS build cache
+desktop/tsconfig.tsbuildinfo
+
+# Temp markdown snapshots
+sidebar-snapshot.md
 
 # VitePress
 docs/.vitepress/dist