feat(frontend): add weather icons and redesign calendar header

Backend changes:
- Add LOCATION configuration option to Settings
- Add /api/system/config endpoint to expose public config
- Implement location priority: config > geolocation > default

Frontend changes:
- Install and integrate weather-icons npm package (Erik Flowers)
- Redesign calendar header with date/time on left, weather/location on right
- Display weather icon using CSS classes instead of SVG components
- Fetch location from backend API on component mount
- Use configured location name (from .env) instead of geocoded result

Layout:
- Left: month/year + current time
- Right: city name + weather description + weather icon

frontend/src/pages/chat/composables/useClientTime.ts

@@ -1,5 +1,4 @@
 import { computed, onMounted, onUnmounted, ref } from 'vue'
-import { Cloud, CloudDrizzle, CloudFog, CloudLightning, CloudRain, CloudSnow, Sun } from 'lucide-vue-next'
 
 export function formatNetworkRate(bytesPerSecond: number | null, online: boolean) {
   if (!online || bytesPerSecond === null) return 'OFFLINE'
@@ -10,10 +9,24 @@ export function formatNetworkRate(bytesPerSecond: number | null, online: boolean
 
 export function useClientTime() {
   const clientTime = ref(new Date())
+  const city = ref('Location')
   const weatherSummary = ref('Weather unavailable')
   const weatherCode = ref<number | null>(null)
   let clientTimeTimer: ReturnType<typeof setInterval> | null = null
 
+  // Load location from backend config
+  async function loadLocation() {
+    try {
+      const response = await fetch('/api/system/config')
+      if (response.ok) {
+        const config = await response.json()
+        city.value = config.location || 'Location'
+      }
+    } catch {
+      city.value = import.meta.env.VITE_LOCATION || 'Location'
+    }
+  }
+
   function updateClientTime() {
     clientTime.value = new Date()
   }
@@ -40,27 +53,48 @@ export function useClientTime() {
 
   const weatherIcon = computed(() => {
     const code = weatherCode.value
-    if (code === 0) return Sun
-    if (code === 1 || code === 2 || code === 3) return Cloud
-    if (code === 45 || code === 48) return CloudFog
-    if ([51, 53, 55, 56, 57].includes(code ?? -1)) return CloudDrizzle
-    if ([61, 63, 65, 66, 67, 80, 81, 82].includes(code ?? -1)) return CloudRain
-    if ([71, 73, 75, 77, 85, 86].includes(code ?? -1)) return CloudSnow
-    if ([95, 96, 99].includes(code ?? -1)) return CloudLightning
-    return Cloud
+    if (code === 0) return 'wi-day-sunny'
+    if (code === 1) return 'wi-day-cloudy'
+    if (code === 2) return 'wi-day-cloudy-gusts'
+    if (code === 3) return 'wi-cloudy'
+    if (code === 45) return 'wi-day-fog'
+    if (code === 48) return 'wi-fog'
+    if ([51, 53].includes(code ?? -1)) return 'wi-day-showers'
+    if ([55, 56, 57].includes(code ?? -1)) return 'wi-showers'
+    if ([61, 63, 65, 80].includes(code ?? -1)) return 'wi-day-rain'
+    if ([66, 67, 81, 82].includes(code ?? -1)) return 'wi-rain'
+    if ([71, 73, 75, 77, 85, 86].includes(code ?? -1)) return 'wi-snow'
+    if ([95, 96, 99].includes(code ?? -1)) return 'wi-thunderstorm'
+    return 'wi-day-sunny'
   })
 
   async function loadWeather(latitude: number, longitude: number) {
     try {
-      const response = await fetch(
+      // Fetch weather data
+      const weatherResp = await fetch(
         `https://api.open-meteo.com/v1/forecast?latitude=${latitude}&longitude=${longitude}&current=temperature_2m,weather_code&timezone=auto`,
       )
-      if (!response.ok) throw new Error('weather request failed')
-      const data = await response.json()
-      const current = data.current ?? {}
+      if (!weatherResp.ok) throw new Error('weather request failed')
+      const weatherData = await weatherResp.json()
+      const current = weatherData.current ?? {}
       weatherCode.value = typeof current.weather_code === 'number' ? current.weather_code : null
       const temp = typeof current.temperature_2m === 'number' ? `${Math.round(current.temperature_2m)}°C` : '--'
       weatherSummary.value = `${weatherCodeLabel(current.weather_code)} ${temp}`
+
+      // Only fetch city name if not already set by config
+      if (city.value === 'Location') {
+        try {
+          const geoResp = await fetch(
+            `https://nominatim.openstreetmap.org/reverse?format=json&lat=${latitude}&lon=${longitude}&zoom=10`,
+          )
+          if (geoResp.ok) {
+            const geoData = await geoResp.json()
+            city.value = geoData.address?.city ?? geoData.address?.town ?? geoData.address?.county ?? geoData.display_name?.split(',')[0] ?? 'Location'
+          }
+        } catch {
+          city.value = 'Location'
+        }
+      }
     } catch {
       weatherCode.value = null
       weatherSummary.value = 'Weather unavailable'
@@ -70,6 +104,7 @@ export function useClientTime() {
   onMounted(() => {
     updateClientTime()
     clientTimeTimer = setInterval(updateClientTime, 1000)
+    void loadLocation()
     if (!navigator.geolocation) {
       weatherCode.value = null
       weatherSummary.value = 'Weather unavailable'
@@ -87,7 +122,7 @@ export function useClientTime() {
   })
 
   return {
-    clientTime, weatherSummary, weatherCode, weatherIcon,
+    clientTime, city, weatherSummary, weatherCode, weatherIcon,
     updateClientTime, formatClientDate, formatClientClock, weatherCodeLabel, loadWeather
   }
 }