feat: add Z-Wave network scan via MQTT gateway

Import a Z-Wave JS UI (zwavejs2mqtt) network over the MQTT gateway API,
mirroring the existing Zigbee pipeline:

- New Z-Wave Import modal + sidebar entry (broker, prefix, gateway name)
- coordinator/router/end-device typing with mesh tree from node neighbors
- import to Pending section or straight to canvas
- Pending Devices gains a Z-Wave source filter
- shared mqtt_common helpers extracted from the zigbee service

ha-relevant: yes

frontend/src/utils/__tests__/zwaveProperties.test.ts

@@ -0,0 +1,38 @@
+import { describe, it, expect } from 'vitest'
+import { isZwaveType, buildZwaveProperties } from '../zwaveProperties'
+
+describe('isZwaveType', () => {
+  it('returns true for zwave types', () => {
+    expect(isZwaveType('zwave_coordinator')).toBe(true)
+    expect(isZwaveType('zwave_router')).toBe(true)
+    expect(isZwaveType('zwave_enddevice')).toBe(true)
+  })
+
+  it('returns false for non-zwave types', () => {
+    expect(isZwaveType('zigbee_router')).toBe(false)
+    expect(isZwaveType('server')).toBe(false)
+    expect(isZwaveType(undefined)).toBe(false)
+    expect(isZwaveType(null)).toBe(false)
+  })
+})
+
+describe('buildZwaveProperties', () => {
+  it('builds Z-Wave ID / Vendor / Model rows, all hidden', () => {
+    const props = buildZwaveProperties({ ieee_address: 'zwave-0xh-2', vendor: 'Aeotec', model: 'ZW100' })
+    expect(props).toEqual([
+      { key: 'Z-Wave ID', value: 'zwave-0xh-2', icon: null, visible: false },
+      { key: 'Vendor', value: 'Aeotec', icon: null, visible: false },
+      { key: 'Model', value: 'ZW100', icon: null, visible: false },
+    ])
+  })
+
+  it('omits empty fields', () => {
+    const props = buildZwaveProperties({ ieee_address: 'zwave-0xh-2', vendor: null, model: undefined })
+    expect(props.map((p) => p.key)).toEqual(['Z-Wave ID'])
+  })
+
+  it('never adds an LQI row', () => {
+    const props = buildZwaveProperties({ ieee_address: 'x', vendor: 'v', model: 'm' })
+    expect(props.some((p) => p.key === 'LQI')).toBe(false)
+  })
+})