Security: Remove hardcoded credentials, enforcing env vars

.env.example

@@ -0,0 +1,13 @@
+# .env Example Configuration
+# Copy this file to .env and adjust the values
+
+# --- Required ---
+NETBOX_URL=http://netbox.example.com
+NETBOX_TOKEN=0123456789abcdef0123456789abcdef01234567
+
+# --- Optional (Defaults shown) ---
+# ZONE_NAME=klenzel.net
+# REVERSE_ZONE_NAME=172.in-addr.arpa
+# REFRESH_INTERVAL=600
+# FALLBACK_NS_HOSTNAME=fks-01-cl-cdns
+# FALLBACK_NS_IP=172.25.16.152