add example env

.env.example

@@ -0,0 +1,35 @@
+# Runtime
+NODE_ENV=development
+MONGODB_URI=mongodb://127.0.0.1:27017/opensquawk
+
+# Authentication
+JWT_SECRET=changeme
+JWT_REFRESH_SECRET=changeme
+
+# OpenAI
+OPENAI_API_KEY=sk-your-openai-key
+OPENAI_PROJECT=
+LLM_MODEL=gpt-5-nano
+TTS_MODEL=tts-1
+VOICE_ID=alloy
+
+# ATC audio generation
+ATC_OUT_DIR=./storage/atc
+USE_SPEACHES=false
+USE_PIPER=false
+PIPER_PORT=5001
+SPEACHES_BASE_URL=
+SPEECH_MODEL_ID=speaches-ai/piper-en_US-ryan-low
+
+# Notifications
+NOTIFY_RESEND_API_KEY=
+NOTIFY_EMAIL_TO=
+NOTIFY_EMAIL_FROM=OpenSquawk <no-reply@opensquawk.dev>
+NOTIFY_SMTP_HOST=
+NOTIFY_SMTP_PORT=587
+NOTIFY_SMTP_SECURE=false
+NOTIFY_SMTP_USER=
+NOTIFY_SMTP_PASS=
+
+# Bootstrap invitations
+BOOTSTRAP_INVITE_DEADLINE=2025-09-01T00:00:00Z