fix: Load all aircraft icon types to prevent fallback to circles - resolves #14

Added missing icon types (heavy, large, light, medium) to the loadIcons() function.
The icon cache was only loading 6 out of 10 available SVG icons, causing aircraft
with weight-based classifications to display as plain circles instead of proper
aircraft icons.

Fixed icon types now loaded:
- ✅ commercial, helicopter, military, cargo, ga, ground (existing)
- ✅ heavy, large, light, medium (newly added)

This ensures all aircraft with known ADS-B emitter categories display the correct
type-specific icons instead of falling back to generic circle markers.

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

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

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

@@ -24,7 +24,7 @@ export class AircraftManager {
     }
 
     async loadIcons() {
-        const iconTypes = ['commercial', 'helicopter', 'military', 'cargo', 'ga', 'ground'];
+        const iconTypes = ['commercial', 'helicopter', 'military', 'cargo', 'ga', 'ground', 'heavy', 'large', 'light', 'medium'];
         
         for (const type of iconTypes) {
             try {