Fix manual switch reverting instantly, add weather forecast

- scheduler: "Show X now" was a true one-shot -- reverted on the very next
  5s tick, causing the flash-to-X-then-flash-back-to-clock behavior. Now
  pins for 5 minutes (still preemptable by Navidrome priority, which stays
  authoritative). Added a "Resume automatic" action/button and status
  display showing what's pinned and until when.
- weather: daily forecast strip (3/5/7 days, selectable in settings) below
  current conditions, via Open-Meteo's daily= params in the same request.
  Fixed a bad symbol choice along the way -- DejaVu Sans has no glyph for
  the partly-cloudy emoji, was rendering as a tofu box; swapped to the
  plain cloud symbol, verified glyph coverage for the whole WMO code table.

web/templates/settings_picture.html

@@ -43,7 +43,7 @@
     <div class="section-label">Display options</div>
     <div class="field">
       <label for="fit">Fit</label>
-      <select id="fit" name="fit" style="width:100%; padding:0.6rem 0.7rem; font-size:0.95rem; font-family:inherit; background:var(--bg); color:var(--text); border:1px solid var(--border); border-radius:8px;">
+      <select id="fit" name="fit">
         <option value="cover" {{ "selected" if settings.fit == "cover" }}>Cover -- fill the screen, cropping edges</option>
         <option value="contain" {{ "selected" if settings.fit == "contain" }}>Contain -- show the whole image, letterboxed</option>
       </select>