Restructure assets to top-level package and add Reset Map button

- Move assets from internal/assets to top-level assets/ package for clean embed directive
- Consolidate all static files in single location (assets/static/)
- Remove duplicate static file locations to maintain single source of truth
- Add Reset Map button to map controls with full functionality
- Implement resetMap() method to return map to calculated origin position
- Store origin in this.mapOrigin for reset functionality
- Fix go:embed pattern to work without parent directory references

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

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

internal/server/server_test.go

@@ -39,17 +39,17 @@ func TestCORSHeaders(t *testing.T) {
 	}
 
 	handler := New(cfg, testStaticFiles)
-	
+
 	req := httptest.NewRequest("OPTIONS", "/api/aircraft", nil)
 	w := httptest.NewRecorder()
-	
+
 	handler.ServeHTTP(w, req)
-	
+
 	if w.Header().Get("Access-Control-Allow-Origin") != "*" {
 		t.Errorf("Expected CORS header, got %s", w.Header().Get("Access-Control-Allow-Origin"))
 	}
-	
+
 	if w.Code != http.StatusOK {
 		t.Errorf("Expected status 200, got %d", w.Code)
 	}
-}
+}