docs: Mark Asus DHCP cutover complete

OPNsense is now the sole DHCP server for LAN (10.4.2.0/24).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/CHANGELOG.md

@@ -76,8 +76,14 @@
   - Required for Pi-hole to accept DNS queries from non-local subnets
 - **Pi-hole Gateway**: Set to 10.4.2.1 (OPNsense) for proper return routing
 
+### Asus DHCP Disabled
+- Disabled DHCP on Asus router
+- OPNsense now sole DHCP server for LAN (10.4.2.0/24)
+- LAN DHCP range: 10.4.2.100-200, DNS: 10.4.2.129 (Pi-hole)
+
 ### Verified Working
 - All VLANs (10, 20, 30) receiving DHCP from OPNsense
+- LAN (10.4.2.0/24) receiving DHCP from OPNsense
 - DNS resolution via Pi-hole from all VLANs
 - Internet access from all VLANs
 - Firewall isolation rules in place