docs: Add firewall fixes and OPNsense config patterns

- Document LAN→IoT firewall rule for HA/Frigate access
- Add OPNsense interface naming (opt1, not lan in config.xml)
- Document IPv6 rule fix that was blocking ruleset loading
- Add pfctl troubleshooting commands
- Mark network isolation tests complete

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

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

docs/TASKS.md

@@ -10,8 +10,9 @@ None currently.
 
 ### Remaining Network Tasks
 - [x] Disable DHCP on Asus router and switch LAN to OPNsense DHCP
-- [ ] Test firewall isolation (IoT device cannot ping LAN device)
-- [ ] Test Smart Home access (Home Assistant can reach IoT devices)
+- [x] Test firewall isolation (IoT device cannot ping LAN device)
+- [x] Test LAN access to IoT (Home Assistant, Frigate can reach IoT devices)
+- [ ] Migrate devices from Asus APs to UniFi APs (to retire Asus routers)
 
 ### Future Network Upgrades
 - [ ] Order hardware (2× GiGaPlus 10G PoE, 2× U7 Pro) for 10G backhaul