feat(devices): migration 025 — lan_devices.icon column

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/db/migrations/025_lan_device_icon.sql

@@ -0,0 +1,4 @@
+-- 025_lan_device_icon.sql
+-- Per-device icon reference: 'set:<set>:<name>' (type icon) or 'brand:<slug>'
+-- (dashboard-icons logo). NULL => UI auto-defaults from the device group.
+ALTER TABLE lan_devices ADD COLUMN IF NOT EXISTS icon text;