feat: standardize OpenAPI route docs metadata (#412)

.env.example

@@ -31,6 +31,9 @@ LOG_LEVEL=warn
 
 # API documentation UI + OpenAPI JSON
 # Default behavior: enabled outside production, disabled in production
+# Recommended:
+#   development/staging: OPENAPI_DOCS_ENABLED=true
+#   production: OPENAPI_DOCS_ENABLED=false
 # OPENAPI_DOCS_ENABLED=true
 
 # Timezone for scheduled reminders (e.g., Europe/Berlin, America/New_York)