Improve aircraft icons and add weight-based color coding

- Replaced simple geometric shapes with detailed, realistic SVG icons for all aircraft types
- Implemented color differentiation based on aircraft weight categories:
  * Light (<7000kg): Sky blue
  * Medium (7000-34000kg): Green
  * Large (34000-136000kg): Orange
  * Heavy (>136000kg): Red
- Created new icons for: commercial airliner, helicopter, cargo aircraft, general aviation, military fighter, ground vehicle
- Updated legend to reflect new weight-based categories
- Modified getAircraftColor() to assign colors based on aircraft category/weight

Closes #17

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

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

assets/static/js/modules/aircraft-manager.js

@@ -215,7 +215,7 @@ export class AircraftManager {
 
     createAircraftIcon(aircraft) {
         const iconType = this.getAircraftIconType(aircraft);
-        const color = this.getAircraftColor(iconType);
+        const color = this.getAircraftColor(iconType, aircraft);
         const size = aircraft.OnGround ? 12 : 16;
         const rotation = aircraft.Track || 0;
         
@@ -277,16 +277,38 @@ export class AircraftManager {
         return 'commercial';
     }
 
-    getAircraftColor(type) {
-        const colors = {
-            commercial: '#00ff88',
-            cargo: '#ff8c00',
-            military: '#ff4444',
-            ga: '#ffff00',
-            ground: '#888888',
-            helicopter: '#ff00ff'  // Magenta for helicopters
-        };
-        return colors[type] || colors.commercial;
+    getAircraftColor(type, aircraft) {
+        // Special colors for specific types
+        if (type === 'military') return '#ff4444';
+        if (type === 'helicopter') return '#ff00ff';
+        if (type === 'ground') return '#888888';
+        if (type === 'ga') return '#ffff00';
+        
+        // For commercial and cargo types, use weight-based colors
+        if (aircraft && aircraft.Category) {
+            const cat = aircraft.Category.toLowerCase();
+            
+            // Check for specific weight ranges in the category string
+            // Light aircraft (< 7000kg) - Sky blue
+            if (cat.includes('light') || cat.includes('7000kg')) {
+                return '#00bfff';
+            }
+            // Medium aircraft (7000-34000kg) - Green  
+            if (cat.includes('medium 7000')) {
+                return '#00ff88';
+            }
+            // Large aircraft (34000-136000kg) - Orange
+            if (cat.includes('medium 34000') || cat.includes('large')) {
+                return '#ff8c00';
+            }
+            // Heavy aircraft (> 136000kg) - Red
+            if (cat.includes('heavy') || cat.includes('136000kg') || cat.includes('super')) {
+                return '#ff0000';
+            }
+        }
+        
+        // Default to green for unknown commercial aircraft
+        return '#00ff88';
     }