update documentation

.env.example

@@ -1,8 +1,21 @@
 # Server port
 PORT=3001
 
+# Public deployment URL used for redirects and generated links
+DEPLOYMENT_URL=https://timetoleave.app
+
 # ÖBB HAFAS API
 HAFAS_URL=https://fahrplan.oebb.at/bin/mgate.exe
+HAFAS_TIMEOUT_MS=10000
+HAFAS_VER=1.36
+HAFAS_LANG=eng
+HAFAS_AID=hf7mcf9bv3nv8g5f
+HAFAS_CLIENT_ID=OEBB
+HAFAS_CLIENT_VER=6020700
+HAFAS_CLIENT_NAME=oebbApp
+
+# Optional ÖBB GTFS enrichment
+OEBB_GTFS_URL=https://static.web.oebb.at/open-data/soll-fahrplan-gtfs/GTFS_Fahrplan_2026.zip
 
 # Nominatim geocoding (OpenStreetMap)
 NOMINATIM_URL=https://nominatim.openstreetmap.org
@@ -19,5 +32,17 @@ WIENER_LINIEN_API_URL=https://api.wienerlinien.at/darwin-v2
 # CORS Configuration
 CORS_ALLOWED_ORIGINS=http://localhost:3000,http://localhost:3001,https://timetoleave.app
 
-# Deployment URL
-DEPLOYMENT_URL=https://timetoleave.app
+# API rate limiting
+API_RATE_LIMIT_MAX_REQUESTS=120
+API_RATE_LIMIT_WINDOW_MS=60000
+
+# Google Calendar OAuth (required for web Google Calendar sync)
+GOOGLE_CLIENT_ID=
+GOOGLE_CLIENT_SECRET=
+GOOGLE_REDIRECT_URI=http://localhost:3000/api/auth/google/callback
+
+# Version returned by /api/health
+APP_VERSION=0.1.0
+
+# Mobile app backend URL for physical device builds
+EXPO_PUBLIC_API_BASE_URL=http://localhost:3000