fix(env): use LOGLEVEL key in root .env.example

Agent-Logs-Url: https://github.com/MervinPraison/PraisonAI/sessions/7fe15070-18b9-4586-ba5e-a70c271db412

Co-authored-by: MervinPraison <454862+MervinPraison@users.noreply.github.com>

Author: Copilot

.env.example

@@ -38,6 +38,6 @@ WHATSAPP_PHONE_NUMBER_ID=...   # WhatsApp phone number ID
 DATABASE_URL=sqlite:///~/.praison/database.sqlite  # Database connection string
 
 # === Optional: Development ===
-LOG_level=INFO                 # Logging level (DEBUG, INFO, WARNING, ERROR)
+LOGLEVEL=INFO                  # Logging level (DEBUG, INFO, WARNING, ERROR)
 CHAINLIT_AUTH_SECRET=...       # Chainlit authentication secret
-DEBUG=false                    # Enable debug mode
+DEBUG=false                    # Enable debug mode