Switch to light map theme by default with dark mode toggle

Major improvements to map theming and aircraft type display:

Map Theme Changes:
- Changed default map from dark to light theme (CartoDB Positron)
- Added night mode toggle button with sun/moon icons
- Both main map and coverage map now switch themes together
- Light theme provides better daylight visibility

Aircraft Type Display:
- Now displays actual ADS-B category directly (e.g., "Medium 34000-136000kg")
- Removed guessing/interpretation of aircraft types
- Icons still use simplified categories for visual distinction
- More accurate and standards-compliant display

This provides a cleaner, more professional appearance with the light map
and gives users accurate ADS-B category information instead of interpreted types.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

assets/static/js/app.js

@@ -103,6 +103,14 @@ class SkyView {
             });
         }
         
+        const toggleDarkModeBtn = document.getElementById('toggle-dark-mode');
+        if (toggleDarkModeBtn) {
+            toggleDarkModeBtn.addEventListener('click', () => {
+                const isDarkMode = this.mapManager.toggleDarkMode();
+                toggleDarkModeBtn.innerHTML = isDarkMode ? '☀️ Light Mode' : '🌙 Night Mode';
+            });
+        }
+        
         // Coverage controls
         const toggleHeatmapBtn = document.getElementById('toggle-heatmap');
         const coverageSourceSelect = document.getElementById('coverage-source');