chore: add .env to gitignore and update JWT secret key

Add .env file to gitignore to prevent accidental commits of sensitive data
Update JWT_SECRET_KEY in .env file for enhanced security

.env

@@ -40,3 +40,5 @@ ACCOUNT_LOCK_DURATION=900
 OTP_VALIDITY_MINUTES=5
 IP_RATE_LIMIT_MAX=10
 IP_RATE_LIMIT_WINDOW=3600
+
+JWT_SECRET_KEY=2c3f5a7b9e1d4f6c8a2b5e7d9c1f3a5b7e9d2c4f6a8b0c1e3f5a7b9d1c3f5e7

.gitignore

@@ -180,3 +180,4 @@ node_modules/
 # Local configuration files
 config.local.*
 settings.local.*
+.env