docs: add troubleshooting quick checks for local setup

Author: however-yir

docs/troubleshooting-quick-checks.md

@@ -0,0 +1,8 @@
+# Troubleshooting Quick Checks
+
+Quick checks when local setup fails:
+
+1. Verify toolchain versions (`java -version`, `node -v`, `python --version`) match project docs.
+2. Confirm required services/ports are available before startup.
+3. Re-run dependency restore with a clean cache when artifacts are corrupted.
+4. Ensure API keys are exported in the same shell/session that starts the app.