Improve type safety for getTrailId function

- Update function signature to accept id as string | number
- Ensure consistent string conversion for all return paths
- Add test coverage for numeric ID cases
- Maintain backward compatibility with existing code

This fixes potential type mismatches where marker IDs can be either
strings or numbers throughout the codebase.

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

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

assets/js/map_helpers.ts

@@ -34,7 +34,7 @@ export function parseTimestamp(timestamp: string | number | Date | undefined): n
 /**
  * Get trail ID from marker data
  */
-export function getTrailId(data: { callsign_group?: string; callsign?: string; id: string }): string {
+export function getTrailId(data: { callsign_group?: string; callsign?: string; id: string | number }): string {
   // Prioritize callsign_group and callsign over extracting from ID
   if (data.callsign_group) {
     return data.callsign_group;
@@ -53,8 +53,8 @@ export function getTrailId(data: { callsign_group?: string; callsign?: string; i
     return withoutPrefix.replace(/_\d+$/, "");
   }
   
-  // For regular IDs, return as-is
-  return data.id;
+  // For regular IDs, return as string
+  return String(data.id);
 }
 
 /**

test/assets/js/map_helpers_test.ts

@@ -92,6 +92,20 @@ describe('map_helpers', () => {
       };
       expect(getTrailId(data)).toBe('REALCALL');
     });
+
+    test('handles numeric ID', () => {
+      const data = {
+        id: 12345
+      };
+      expect(getTrailId(data)).toBe('12345');
+    });
+
+    test('handles numeric historical ID', () => {
+      const data = {
+        id: 'hist_MYCALL_12345'
+      };
+      expect(getTrailId(data)).toBe('MYCALL');
+    });
   });
 
   describe('saveMapState', () => {