feat(catalog): migration 005 — power-distribution devices

Adds 5 built-in device_types (project_id NULL, built_in=1):
- Multi-plug 3/4/5/6 (kind=hub, 🔌) — Power × N+1 (1 in + N out)
- Wifi-plug (kind=accessory, 📶) — Power × 2 pass-through outlet

The solver treats every Power port identically regardless of in/out
direction; m knows which end is which from the physical setup.

Tests:
- TestSeed_BuiltInDeviceTypes: built-in count rises from 16 → 21.
- TestSeed_PortProfiles: new entries' port totals.
- TestSeed_PowerCatalog (new, table-driven): asserts kind, icon, and
  the single Power port row for each of the 5 new types.

internal/db/migrations/005_catalog_power.sql

@@ -0,0 +1,32 @@
+-- mCables v5 — catalog: power-distribution devices.
+-- Adds 5 built-in device_types (project_id NULL, built_in=1).
+--
+-- Multi-plug N exposes Power × (N+1) ports — one input + N outputs. The
+-- solver treats every Power port identically regardless of in/out
+-- direction; m knows which end is which from the physical setup.
+--
+-- Wifi-plug is a pass-through outlet (Power × 2: one in, one out).
+
+INSERT INTO device_types (name, kind, icon, built_in, description) VALUES
+    ('Multi-plug 3', 'hub',       '🔌', 1, '3-way power strip (1 in + 3 out)'),
+    ('Multi-plug 4', 'hub',       '🔌', 1, '4-way power strip (1 in + 4 out)'),
+    ('Multi-plug 5', 'hub',       '🔌', 1, '5-way power strip (1 in + 5 out)'),
+    ('Multi-plug 6', 'hub',       '🔌', 1, '6-way power strip (1 in + 6 out)'),
+    ('Wifi-plug',    'accessory', '📶', 1, 'WiFi-controllable pass-through outlet');
+
+-- Port profiles. cable_types id 1 = Power (seeded in 001).
+
+INSERT INTO device_type_ports (device_type_id, cable_type_id, label_prefix, count, edge, sort_order)
+    SELECT id, 1, 'Power', 4, 'bottom', 0 FROM device_types WHERE name='Multi-plug 3' AND project_id IS NULL;
+
+INSERT INTO device_type_ports (device_type_id, cable_type_id, label_prefix, count, edge, sort_order)
+    SELECT id, 1, 'Power', 5, 'bottom', 0 FROM device_types WHERE name='Multi-plug 4' AND project_id IS NULL;
+
+INSERT INTO device_type_ports (device_type_id, cable_type_id, label_prefix, count, edge, sort_order)
+    SELECT id, 1, 'Power', 6, 'bottom', 0 FROM device_types WHERE name='Multi-plug 5' AND project_id IS NULL;
+
+INSERT INTO device_type_ports (device_type_id, cable_type_id, label_prefix, count, edge, sort_order)
+    SELECT id, 1, 'Power', 7, 'bottom', 0 FROM device_types WHERE name='Multi-plug 6' AND project_id IS NULL;
+
+INSERT INTO device_type_ports (device_type_id, cable_type_id, label_prefix, count, edge, sort_order)
+    SELECT id, 1, 'Power', 2, 'bottom', 0 FROM device_types WHERE name='Wifi-plug' AND project_id IS NULL;