Add Daikin local-API driver — MAC-matched subnet sweep instead of UDP broadcast

Daikin BRP069/BRP072-class units are WiFi/DHCP with no fixed IP. hvac's backend
runs as a Docker container on its own bridge network (not directly on the LXC's
admin-VLAN NIC), so UDP broadcast discovery risked silently failing to egress —
instead, every unit is identified by MAC (external_ref), and a background poller
periodically HTTP-sweeps the configured subnet CIDR and matches replies by MAC,
self-healing zone_devices.device_ip whenever a lease changes. Only needs plain
outbound HTTP, same path already proven by the MHI Modbus TCP driver.

- lib/drivers/daikin.js: discover()/getStatus()/setTarget() against the local
  /common/basic_info + /aircon/get_control_info + /aircon/set_control_info API
  (confirmed live against firmware 4_2_303, 2026-08-25). Mode/fan-rate encoding
  taken from community reverse-engineering, not yet verified against a live
  setTarget() call — flagged in comments for first real control test.
- lib/daikin-poller.js: 60s status poll (cached IP) + 5min subnet resweep
  (self-heal IP + auto-register new units, never auto-assigned to a zone).
- lib/device-registry.js: shared discover-upsert, extracted so both the manual
  Discover button and the background sweep record device_ip the same way.
- ac-control.js / routes/override.js: daikin-status/daikin-control endpoints
  and commandAcDevice() branch, mirroring the existing MHI control path.
- Settings page: new "Daikin subnet (CIDR)" field (daikin_subnet_cidr config
  key) — sweeps do nothing until this is set.
- Frontend: DaikinControlPanel.tsx (on/off/mode/setpoint/fan), wired into
  ZoneDetailModal; daikin moved from NOT_YET_IMPLEMENTED to a real driver.

Backend node --check and frontend tsc --noEmit both clean.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/api.ts

@@ -1,6 +1,6 @@
 import type {
   Zone, ZoneStatus, Device, DevicePhoto, ActivityEntry, NewbookSite, AppConfig,
-  MhiGateway, MhiStatus, ActiveAcTemplate,
+  MhiGateway, MhiStatus, ActiveAcTemplate, DaikinStatus,
 } from './types'
 
 const BASE = '/hvac/api'
@@ -144,6 +144,14 @@ export function sendMhiControl(deviceId: number, body: { onOff?: boolean; mode?:
   return request(`/devices/${deviceId}/mhi-control`, { method: 'POST', body: JSON.stringify(body) })
 }
 
+// Daikin manual control (device-level — daikin rows only)
+export function fetchDaikinStatus(deviceId: number): Promise<DaikinStatus> {
+  return request(`/devices/${deviceId}/daikin-status`)
+}
+export function sendDaikinControl(deviceId: number, body: { onOff?: boolean; mode?: string; tempC?: number; fanSpeed?: string }): Promise<{ ok: boolean }> {
+  return request(`/devices/${deviceId}/daikin-control`, { method: 'POST', body: JSON.stringify(body) })
+}
+
 // Config / settings
 export function fetchConfig(): Promise<AppConfig> {
   return request('/config')