Add dartdoc comments and example for pub.dev scoring

example/example.dart

@@ -0,0 +1,70 @@
+// ignore_for_file: avoid_print
+import 'package:h3_core/h3_core.dart';
+
+void main() {
+  // Convert a coordinate to an H3 cell index at resolution 9.
+  final sf = LatLng(37.7749295, -122.4194155);
+  final cell = latLngToCell(sf, 9);
+  print('H3 cell: ${cell.toHex()}'); // e.g. 8928308280fffff
+
+  // Get the center of the cell.
+  final center = cellToLatLng(cell);
+  print('Center: ${center.lat}, ${center.lng}');
+
+  // Inspect the cell.
+  print('Resolution: ${getResolution(cell)}');
+  print('Valid: ${isValidCell(cell)}');
+  print('Pentagon: ${isPentagon(cell)}');
+
+  // Get the cell boundary vertices.
+  final boundary = cellToBoundary(cell);
+  print('Boundary vertices: ${boundary.vertices.length}');
+
+  // Find neighbors within 1 grid step.
+  final neighbors = gridDisk(cell, 1);
+  print('Neighbors (k=1): ${neighbors.length}');
+
+  // Grid distance between two cells.
+  final other = neighbors.last;
+  final distance = gridDistance(cell, other);
+  print('Grid distance: $distance');
+
+  // Hierarchy: parent and children.
+  final parent = cellToParent(cell, 8);
+  print('Parent (res 8): ${parent.toHex()}');
+
+  final children = cellToChildren(cell, 10);
+  print('Children (res 10): ${children.length}');
+
+  // Compact and uncompact.
+  final compacted = compactCells(children);
+  print('Compacted: ${compacted.length}');
+
+  // Measurements.
+  final area = cellAreaKm2(cell);
+  print('Cell area: ${area.toStringAsFixed(4)} km²');
+
+  final dist = greatCircleDistanceKm(sf, LatLng(40.7128, -74.0060));
+  print('SF to NYC: ${dist.toStringAsFixed(1)} km');
+
+  // Directed edges.
+  final neighbor = neighbors[1];
+  if (areNeighborCells(cell, neighbor)) {
+    final edge = cellsToDirectedEdge(cell, neighbor);
+    print('Edge: ${edge.toHex()}');
+    print('Edge length: ${edgeLengthKm(edge).toStringAsFixed(3)} km');
+  }
+
+  // Region: fill a polygon with cells.
+  final polygon = GeoPolygon([
+    LatLng(37.78, -122.42),
+    LatLng(37.78, -122.41),
+    LatLng(37.77, -122.41),
+    LatLng(37.77, -122.42),
+  ]);
+  final filled = polygonToCells(polygon, 9);
+  print('Cells in polygon: ${filled.length}');
+
+  // Version info.
+  print('h3_core ${H3Version.package}, H3 native ${H3Version.native}');
+}

lib/src/errors.dart

@@ -1,10 +1,18 @@
-/// Base exception for all H3 errors.
+/// Exception thrown when an H3 operation fails.
+///
+/// Each error has a numeric [code] corresponding to the H3 C library error
+/// codes and a human-readable [message].
 class H3Exception implements Exception {
+  /// The H3 error code (1–19).
   final int code;
+
+  /// A human-readable description of the error.
   final String message;
 
+  /// Creates an [H3Exception] with the given [code] and [message].
   const H3Exception(this.code, this.message);
 
+  /// Creates an [H3Exception] from an H3 C library error [code].
   factory H3Exception.fromCode(int code) {
     return switch (code) {
       1 => const H3Exception(1, 'Operation failed'),