test(client): 用例名统一为 should_<期望>_when_<条件>（155/155）

为什么：红线第 8 条门禁立即生效，要求 Flutter 测试命名合规；此前 155 条用例名是英文自然语言
或中文描述，合规数 0/155，属存量欠账，按"先补齐再上新功能"在本批处理。

- 25 个测试文件、155 条用例改名，按「文件 + 旧名」精确定位，每条断言命中恰好 1 次才替换
- 只改名字字面量：改动行 155 删 + 155 增，无一行不含字符串字面量（断言与用例体零改动）
- 门禁：dart analyze lib test = No issues found；flutter test = 155 全过

test/core/android_picture_in_picture_test.dart

@@ -28,7 +28,7 @@ void main() {
   });
 
   group('platform support', () {
-    test('android is the only supported target', () {
+    test('should_support_only_android_when_target_is_checked', () {
       debugDefaultTargetPlatformOverride = TargetPlatform.android;
       expect(pip().isPlatformSupported, isTrue);
 
@@ -50,7 +50,7 @@ void main() {
   });
 
   group('enter', () {
-    test('is refused without touching the channel off android', () async {
+    test('should_refuse_without_touching_channel_when_target_is_not_android', () async {
       debugDefaultTargetPlatformOverride = TargetPlatform.iOS;
       final calls = <MethodCall>[];
       messenger.setMockMethodCallHandler(channel, (call) async {
@@ -63,7 +63,7 @@ void main() {
       expect(calls, isEmpty);
     });
 
-    test('a missing native answer counts as a refusal', () async {
+    test('should_count_as_refused_when_native_answer_is_missing', () async {
       debugDefaultTargetPlatformOverride = TargetPlatform.android;
       messenger.setMockMethodCallHandler(channel, (call) async => null);
       addTearDown(() => messenger.setMockMethodCallHandler(channel, null));
@@ -71,7 +71,7 @@ void main() {
       expect(await pip().enter(), isFalse);
     });
 
-    test('a native success is reported as entered', () async {
+    test('should_report_entered_when_native_call_succeeds', () async {
       debugDefaultTargetPlatformOverride = TargetPlatform.android;
       final calls = <MethodCall>[];
       messenger.setMockMethodCallHandler(channel, (call) async {
@@ -87,7 +87,7 @@ void main() {
   });
 
   group('state listener', () {
-    test('pip state changes reach the listener in order', () async {
+    test('should_deliver_pip_state_changes_in_order_when_native_events_arrive', () async {
       final received = <bool>[];
       pip().setStateListener(received.add);
 
@@ -97,7 +97,7 @@ void main() {
       expect(received, [true, false]);
     });
 
-    test('only a literal true is read as enabled', () async {
+    test('should_treat_only_literal_true_as_enabled_when_native_value_arrives', () async {
       final received = <bool>[];
       pip().setStateListener(received.add);
 
@@ -108,7 +108,7 @@ void main() {
       expect(received, [false, false, false]);
     });
 
-    test('unrelated native methods are ignored', () async {
+    test('should_ignore_unrelated_native_methods_when_events_arrive', () async {
       final received = <bool>[];
       pip().setStateListener(received.add);
 
@@ -118,7 +118,7 @@ void main() {
       expect(received, [true]);
     });
 
-    test('clearing the listener silences later callbacks', () async {
+    test('should_silence_later_callbacks_when_listener_is_cleared', () async {
       final received = <bool>[];
       final observer = pip()..setStateListener(received.add);
       await sendToDart('onPipChanged', true);

test/core/api_client_test.dart

@@ -14,7 +14,7 @@ void main() {
     return jsonEncode({'code': code, 'message': message, 'data': data});
   }
 
-  test('should return the data field when the envelope code is zero', () async {
+  test('should_return_data_field_when_envelope_code_is_zero', () async {
     final adapter = FakeHttpAdapter(
       (_) async => FakeHttpResponse(envelope({'id': 7})),
     );
@@ -24,7 +24,7 @@ void main() {
     expect((data as Map)['id'], 7);
   });
 
-  test('should throw an ApiException carrying the server message when the envelope code is not zero', () async {
+  test('should_throw_api_exception_with_server_message_when_envelope_code_is_not_zero', () async {
     final adapter = FakeHttpAdapter(
       (_) async => FakeHttpResponse(
         envelope(null, code: 40001, message: '邮箱格式不正确'),
@@ -42,7 +42,7 @@ void main() {
     );
   });
 
-  test('should map a body without envelope to an ApiException carrying the http status', () async {
+  test('should_map_to_api_exception_with_http_status_when_body_has_no_envelope', () async {
     final adapter = FakeHttpAdapter((_) async => FakeHttpResponse('oops', 502));
     final client = ApiClient(baseUrl: 'http://127.0.0.1:8081', adapter: adapter);
 
@@ -54,7 +54,7 @@ void main() {
     );
   });
 
-  test('should send the bearer token and the device header when both are available', () async {
+  test('should_send_bearer_token_and_device_header_when_both_are_available', () async {
     final adapter = FakeHttpAdapter((_) async => FakeHttpResponse(envelope(null)));
     final client = ApiClient(
       baseUrl: 'http://127.0.0.1:8081',
@@ -71,7 +71,7 @@ void main() {
     expect(request.headers['Accept'], 'application/json');
   });
 
-  test('should put the query map into the request uri', () async {
+  test('should_put_query_map_into_request_uri_when_query_is_given', () async {
     final adapter = FakeHttpAdapter((_) async => FakeHttpResponse(envelope(null)));
     final client = ApiClient(baseUrl: 'http://127.0.0.1:8081', adapter: adapter);
 
@@ -83,7 +83,7 @@ void main() {
     expect(uri.queryParameters['page'], '2');
   });
 
-  test('should not refresh the token when the call opts out of auth retry', () async {
+  test('should_skip_refresh_when_call_opts_out_of_auth_retry', () async {
     var refreshed = false;
     final adapter = FakeHttpAdapter(
       (_) async => FakeHttpResponse(envelope(null, code: 401, message: '登录已过期')),