Show weather compensation summary banner on the Dashboard

New lib/ac-template.js factors the "which occupied AC template applies
right now" resolution out of scheduler.js (dedupes the tier-pick loop
that used to live separately in scheduler.js and status.js) into a
shared resolveOccupiedAcTier()/resolveGlobalOccupiedAcTemplate() pair.
GET /api/status now returns active_ac_template alongside weather_peak_c.

Dashboard shows a small banner above the zone grid: "Forecast high
today: XC" + "Aircon default: ON, 20C, High fan — Warm tier" — so staff
don't have to visit Settings to see what today's weather tier resolved
to.

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

frontend/src/pages/Dashboard.tsx

@@ -1,24 +1,32 @@
 import { useEffect, useState, useCallback } from 'react'
 import { WifiOff } from 'lucide-react'
 import { fetchStatus } from '../api'
-import type { ZoneStatus } from '../types'
+import type { ZoneStatus, ActiveAcTemplate } from '../types'
 import ZoneCard from '../components/ZoneCard'
 import ZoneDetailModal from '../components/ZoneDetailModal'
 
 const POLL_MS = 30000
 
+function cap(s: string) {
+  return s[0].toUpperCase() + s.slice(1)
+}
+
 export default function Dashboard() {
   const [zones, setZones] = useState<ZoneStatus[]>([])
   const [mqttConnected, setMqttConnected] = useState(true)
   const [loading, setLoading] = useState(true)
   const [error, setError] = useState('')
   const [selected, setSelected] = useState<ZoneStatus | null>(null)
+  const [weatherPeakC, setWeatherPeakC] = useState<number | null>(null)
+  const [activeAcTemplate, setActiveAcTemplate] = useState<ActiveAcTemplate | null>(null)
 
   const load = useCallback(() => {
     fetchStatus()
       .then(res => {
         setZones(res.zones)
         setMqttConnected(res.mqtt_connected)
+        setWeatherPeakC(res.weather_peak_c)
+        setActiveAcTemplate(res.active_ac_template)
         setError('')
       })
       .catch(e => setError(e instanceof Error ? e.message : 'Failed to load status'))
@@ -42,6 +50,23 @@ export default function Dashboard() {
         <h1>Dashboard</h1>
       </div>
 
+      {weatherPeakC != null && activeAcTemplate && (
+        <div className="card" style={{
+          display: 'flex', alignItems: 'center', gap: 20, flexWrap: 'wrap',
+          marginBottom: 16, fontSize: 13,
+        }}>
+          <div>
+            Forecast high today: <strong style={{ color: 'var(--gold)' }}>{weatherPeakC}°C</strong>
+          </div>
+          <div className="muted">
+            Aircon default: <strong style={{ color: 'var(--text-dark)' }}>{activeAcTemplate.power === 'on' ? 'ON' : 'OFF'}</strong>
+            {activeAcTemplate.setpoint != null && <>, {activeAcTemplate.setpoint}°C</>}
+            {activeAcTemplate.fan_speed && <>, {cap(activeAcTemplate.fan_speed)} fan</>}
+            {activeAcTemplate.tierApplied && <> — <strong>{cap(activeAcTemplate.tierApplied)}</strong> tier</>}
+          </div>
+        </div>
+      )}
+
       {error && <div className="error-banner">{error}</div>}
       {!mqttConnected && (
         <div className="error-banner" style={{ display: 'flex', alignItems: 'center', gap: 8 }}>