Show a visible source icon for Open-Meteo fallback values on NWS

Replace the hidden hover-only native title with a dedicated SourceTooltip
component: a small ⓘ badge rendered inline next to Pressure and UV values
(Current + Details views) that reveals a styled tooltip on hover/focus,
so it is obvious the value came from the non-selected source (Open-Meteo)
instead of requiring discovery by hovering the data.

src/components/CurrentWeather.svelte

@@ -1,6 +1,7 @@
 <script>
   import { app } from '../lib/stores/app.svelte.js'
   import { getWeatherInfo, getWeatherSeverity } from '../lib/api/weather-codes.js'
+  import SourceTooltip from './SourceTooltip.svelte'
 
   const data = $derived(app.forecastData)
   const current = $derived(data?.current)
@@ -71,15 +72,15 @@
         <span class="metric-value">{Math.round(current.wind_speed_10m)} {windUnit}</span>
         <span class="metric-sub">{windCompass(current.wind_direction_10m)}</span>
       </div>
-      <div class="metric-card" title={fbPressure ? 'Pressure from Open-Meteo — NWS does not provide it' : undefined}>
+      <div class="metric-card">
         <span class="metric-icon">🌡️</span>
         <span class="metric-label">Pressure</span>
-        <span class="metric-value">{Math.round(current.pressure_msl || 0)} hPa</span>
+        <span class="metric-value">{Math.round(current.pressure_msl || 0)} hPa{#if fbPressure}<SourceTooltip label="Pressure from Open-Meteo — NWS does not provide it" />{/if}</span>
       </div>
-      <div class="metric-card" title={fbUv ? 'UV index from Open-Meteo — NWS does not provide it' : undefined}>
+      <div class="metric-card">
         <span class="metric-icon">☀️</span>
         <span class="metric-label">UV Index</span>
-        <span class="metric-value">{current.uv_index != null ? Math.round(current.uv_index) : '--'}</span>
+        <span class="metric-value">{current.uv_index != null ? Math.round(current.uv_index) : '--'}{#if fbUv}<SourceTooltip label="UV index from Open-Meteo — NWS does not provide it" />{/if}</span>
         {#if current.uv_index != null}
           <span class="metric-sub">{current.uv_index <= 2 ? 'Low' : current.uv_index <= 5 ? 'Moderate' : current.uv_index <= 7 ? 'High' : 'Very High'}</span>
         {/if}

src/components/SourceTooltip.svelte

@@ -0,0 +1,79 @@
+<script>
+  /** Small info badge whose tooltip explains the value came from the
+   * non-selected source (e.g. Open-Meteo while NWS is selected). */
+  let { label = '' } = $props()
+</script>
+
+<span class="srctip" tabindex="0" role="note" aria-label={label}>
+  <span class="srctip-icon" aria-hidden="true">ⓘ</span>
+  <span class="srctip-bubble">{label}</span>
+</span>
+
+<style>
+  .srctip {
+    position: relative;
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    width: 17px;
+    height: 17px;
+    margin-left: 6px;
+    vertical-align: middle;
+    cursor: help;
+    flex: none;
+    color: var(--color-primary, #38bdf8);
+  }
+  .srctip-icon {
+    font-size: 0.98rem;
+    line-height: 1;
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+  }
+  .srctip-bubble {
+    position: absolute;
+    bottom: calc(100% + 7px);
+    left: 50%;
+    transform: translateX(-50%);
+    width: max-content;
+    max-width: 210px;
+    padding: 7px 10px;
+    border-radius: 7px;
+    background: #0b1220;
+    color: #e2e8f0;
+    font-size: 0.74rem;
+    font-weight: 500;
+    line-height: 1.4;
+    white-space: normal;
+    text-align: left;
+    box-shadow: 0 5px 16px rgba(0, 0, 0, 0.4);
+    border: 1px solid rgba(255, 255, 255, 0.1);
+    opacity: 0;
+    visibility: hidden;
+    pointer-events: none;
+    transition: opacity 0.12s ease, visibility 0.12s ease;
+    z-index: 60;
+  }
+  /* small arrow */
+  .srctip-bubble::after {
+    content: '';
+    position: absolute;
+    top: 100%;
+    left: 50%;
+    transform: translateX(-50%);
+    border: 5px solid transparent;
+    border-top-color: #0b1220;
+  }
+  .srctip:hover .srctip-bubble,
+  .srctip:focus .srctip-bubble,
+  .srctip:focus-visible .srctip-bubble {
+    opacity: 1;
+    visibility: visible;
+  }
+  .srctip:focus,
+  .srctip:focus-visible {
+    outline: 2px solid var(--color-primary, #38bdf8);
+    outline-offset: 2px;
+    border-radius: 50%;
+  }
+</style>

src/components/WeatherDetail.svelte

@@ -1,6 +1,7 @@
 <script>
   import { app } from '../lib/stores/app.svelte.js'
   import { getWeatherInfo } from '../lib/api/weather-codes.js'
+  import SourceTooltip from './SourceTooltip.svelte'
 
   const data = $derived(app.forecastData)
   const current = $derived(data?.current)
@@ -97,7 +98,7 @@
           </div>
           <div class="detail-row">
             <span>Pressure</span>
-            <span class="detail-value" title={fbPressure ? 'Pressure from Open-Meteo — NWS does not provide it' : undefined}>{Math.round(current.pressure_msl || 0)} hPa</span>
+            <span class="detail-value">{Math.round(current.pressure_msl || 0)} hPa{#if fbPressure}<SourceTooltip label="Pressure from Open-Meteo — NWS does not provide it" />{/if}</span>
           </div>
           <div class="detail-row">
             <span>Feels Like</span>
@@ -119,11 +120,12 @@
         <div class="detail-body">
           <div class="detail-row">
             <span>UV Index</span>
-            <span class="detail-value" title={fbUv ? 'UV index from Open-Meteo — NWS does not provide it' : undefined}>
+            <span class="detail-value">
               {current.uv_index != null ? Math.round(current.uv_index) : '--'}
               {#if current.uv_index != null}
                 <span class="uv-badge uv-{getUVLevel(current.uv_index).toLowerCase().replace(' ', '-')}">{getUVLevel(current.uv_index)}</span>
               {/if}
+              {#if fbUv}<SourceTooltip label="UV index from Open-Meteo — NWS does not provide it" />{/if}
             </span>
           </div>
           <div class="detail-row">
@@ -136,7 +138,7 @@
           </div>
           <div class="detail-row">
             <span>Max UV Today</span>
-            <span class="detail-value" title={fbUv ? 'UV from Open-Meteo — NWS does not provide it' : undefined}>{daily?.uv_index_max?.[0] != null ? Math.round(daily.uv_index_max[0]) : '--'}</span>
+            <span class="detail-value">{daily?.uv_index_max?.[0] != null ? Math.round(daily.uv_index_max[0]) : '--'}{#if fbUv}<SourceTooltip label="UV from Open-Meteo — NWS does not provide it" />{/if}</span>
           </div>
         </div>
       </div>