Implement hierarchical burg placement and route generation system

Major Changes:
- Enhanced burg placement system with three-tier hierarchy:
  * Primary centers (capitals + large ports) connected by main roads
  * Regional centers (plaza burgs) connected by secondary roads
  * Local settlements connected by trails to existing network

Burg Placement Improvements (burgs-and-states.js):
- Added identifyLargePorts() function to mark coastal settlements as major population centers
- Implemented placeRegionalCenters() function for strategic plaza burg placement
- Enhanced placeTowns() with hierarchical scoring based on distance to major centers
- Updated population calculations to respect settlement hierarchy
- Modified defineBurgFeatures() to guarantee plazas for regional centers

Route Generation Overhaul (routes-generator.js):
- Created hierarchical route system eliminating overlapping routes:
  * Main roads connect primary population centers (capitals + large ports)
  * Secondary roads connect plaza burgs to main network and each other
  * Trails connect isolated settlements to nearest existing routes
- Added filtered burg categorization to prevent duplicate connections
- Implemented intelligent pathfinding that integrates with existing routes
- Fixed getLength() function with fallback calculation for DOM timing issues

CSV Export Enhancement (routes-overview.js):
- Updated routes CSV export to include new "secondary" route type
- Added documentation for supported route types in export function

Technical Features:
- Distance-based population gradients radiating from major centers
- Urquhart graph algorithm for optimal route networks
- Integration with existing pathfinding cost system
- Proper route merging and connection tracking
- Robust error handling for route length calculations

Result:
- Realistic settlement hierarchy with proper population distribution
- Non-overlapping transportation network with clear purpose for each route type
- Radial patterns from major centers through regional hubs to local settlements
- Enhanced world-building with economically logical settlement placement

modules/ui/routes-overview.js

@@ -99,6 +99,7 @@ function overviewRoutes() {
   }
 
   function downloadRoutesData() {
+    // Export all route types: roads (main), secondary (plaza connections), trails, searoutes
     let data = "Id,Route,Group,Length\n"; // headers
 
     body.querySelectorAll(":scope > div").forEach(function (el) {