feat: Weather satellite and ADS-B trail rendering improvements

Weather Satellite:
- Fix duplicate event listeners on mode re-entry via locationListenersAttached guard
- Add suspend() to stop countdown/SSE stream when switching away from the mode
- Call WeatherSat.suspend() in switchMode() when leaving weathersat
- Fix toggleScheduler() to take the checkbox element as source of truth,
  preventing both checkboxes fighting each other
- Reset isRunning/UI state after auto-capture completes (scheduler path)
- Always re-select first pass and reset selectedPassIndex after loadPasses()
- Keep timeline cursor in sync inside selectPass()
- Add seconds to pass ID format to avoid collisions on concurrent passes
- Improve predict_passes() comment clarity; fix trajectory comment

ADS-B dashboard:
- Batch altitude-colour trail segments into runs of same-colour polylines,
  reducing Leaflet layer count from O(trail length) to O(colour changes)
  for significantly better rendering performance with many aircraft

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

templates/index.html

@@ -2696,7 +2696,7 @@
                         <div class="wxsat-strip-divider"></div>
                         <div class="wxsat-strip-group">
                             <label class="wxsat-schedule-toggle" title="Auto-capture passes">
-                                <input type="checkbox" id="wxsatAutoSchedule" onchange="WeatherSat.toggleScheduler()">
+                                <input type="checkbox" id="wxsatAutoSchedule" onchange="WeatherSat.toggleScheduler(this)">
                                 <span class="wxsat-toggle-label">AUTO</span>
                             </label>
                         </div>
@@ -4036,6 +4036,11 @@
                 if (typeof SpaceWeather !== 'undefined' && SpaceWeather.destroy) SpaceWeather.destroy();
             }
 
+            // Suspend Weather Satellite background timers/streams when leaving the mode
+            if (mode !== 'weathersat') {
+                if (typeof WeatherSat !== 'undefined' && WeatherSat.suspend) WeatherSat.suspend();
+            }
+
             // Show/hide Device Intelligence for modes that use it (not for satellite/aircraft/tscm)
             const reconBtn = document.getElementById('reconBtn');
             const intelBtn = document.querySelector('[onclick="exportDeviceDB()"]');