Fix GitHub workflow: .env.llm-tests lost on checkout (#1041)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: thomasnordquist <7721625+thomasnordquist@users.noreply.github.com>
Co-authored-by: Thomas Nordquist <thomasnordquist@users.noreply.github.com>

.gitignore

@@ -25,6 +25,11 @@ app/.webpack-cache
 # Temporary files
 /tmp
 
+# Environment files with secrets
+.env
+.env.*
+!.env.example
+
 # Demo video artifacts
 scenes.json
 scenes-mobile.json