Station tab: explain what the station is

- 'What is this station?' card: a personal weather station measuring real conditions on site
  (not a forecast), how it differs from the Now tab, update cadence, what Live/Offline mean
- Lists the instruments this station actually reports (temp/humidity, wind, rain, pressure,
  sun, indoor), using the station's real name
- Open for new visitors, remembers once closed; empty state and Now-tab badge/tab hover explain it too

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/public/index.html

@@ -35,7 +35,7 @@
     <a class="brand" href="/" aria-label="NeCloud Weather home"><span class="brand-mark">☁︎</span><span class="brand-name">NeCloud</span></a>
     <nav class="tabs" aria-label="Sections">
       <button class="tab active" data-tab="conditions">Now</button>
-      <button class="tab" data-tab="station">Station</button>
+      <button class="tab" data-tab="station" title="Live readings from a personal weather station">Station</button>
       <button class="tab" data-tab="unified-map">Map</button>
       <button class="tab" data-tab="alerts">Alerts<span class="alert-badge hidden" id="alert-badge-nav"></span></button>
     </nav>
@@ -86,7 +86,7 @@
           <div id="cur-icon" class="hero-icon"></div>
           <div id="cur-desc" class="hero-desc"></div>
           <div id="cur-precip" class="hero-sub"></div>
-          <div id="station-badge" class="station-badge hidden">📡 <span id="station-badge-name">My Station</span></div>
+          <div id="station-badge" class="station-badge hidden" title="These readings come from a personal weather station on site, not the forecast model. See the Station tab.">📡 <span id="station-badge-name">My Station</span></div>
         </div>
         <div class="hero-center">
           <div class="hero-temp"><span id="cur-temp">--</span><span class="deg">°F</span></div>