Rename Dart package hanzo -> hanzo_base

pub.dev names 'hanzo' and 'base' are taken by unrelated packages;
'hanzo_base' is the correct available name. Renames the library
(lib/hanzo.dart -> lib/hanzo_base.dart), example, and test, and
fixes all package: imports, README, badge, and pubspec repository
to hanzo-dart/base. dart analyze --fatal-infos + dart test green;
pub publish --dry-run clean (0 warnings).

README.md

@@ -1,6 +1,6 @@
-# hanzo — Dart SDK for Hanzo Base
+# hanzo_base — Dart SDK for Hanzo Base
 
-[![pub package](https://img.shields.io/pub/v/hanzo.svg)](https://pub.dev/packages/hanzo)
+[![pub package](https://img.shields.io/pub/v/hanzo_base.svg)](https://pub.dev/packages/hanzo_base)
 
 Small, typed Dart client for [Hanzo Base](https://hanzo.ai), the reactive
 backend. Auth is [Hanzo IAM](https://hanzo.id)-native: the client holds the
@@ -14,11 +14,11 @@ apps need: auth, records/collections CRUD, realtime (SSE), and files.
 
 ```yaml
 dependencies:
-  hanzo: ^0.1.0
+  hanzo_base: ^0.1.0
 ```
 
 ```dart
-import 'package:hanzo/hanzo.dart';
+import 'package:hanzo_base/hanzo_base.dart';
 
 final base = HanzoBase('https://base.hanzo.ai');
 ```

example/hanzo_base_example.dart

@@ -1,4 +1,4 @@
-import 'package:hanzo/hanzo.dart';
+import 'package:hanzo_base/hanzo_base.dart';
 
 Future<void> main() async {
   final base = HanzoBase('https://base.hanzo.ai');

pubspec.yaml

@@ -1,9 +1,9 @@
-name: hanzo
+name: hanzo_base
 description: Dart SDK for Hanzo Base — reactive backend records, realtime, and files with Hanzo IAM-native auth.
 version: 0.1.0
-repository: https://github.com/hanzoai/base
+repository: https://github.com/hanzo-dart/base
 homepage: https://hanzo.ai
-issue_tracker: https://github.com/hanzoai/base/issues
+issue_tracker: https://github.com/hanzo-dart/base/issues
 
 environment:
   sdk: '>=3.0.0 <4.0.0'

test/hanzo_base_test.dart

@@ -1,6 +1,6 @@
 import 'dart:convert';
 
-import 'package:hanzo/hanzo.dart';
+import 'package:hanzo_base/hanzo_base.dart';
 import 'package:http/http.dart' as http;
 import 'package:http/testing.dart';
 import 'package:test/test.dart';