feat: add command hint for generating login attempt salt

Author: zerox80

.env.example

@@ -25,6 +25,7 @@ ADMIN_PASSWORD=change-me-min-12-chars
 
 # Login Security Configuration
 # Required: high-entropy salt used to hash login attempt identifiers (protects rate limiting)
+#openssl rand -base64 48
 LOGIN_ATTEMPT_SALT=generate-a-random-64-byte-string
 
 # Logging Configuration