feat(apps): establish shared mobile design system

apps/service_app/lib/ui/features/auth/login_page.dart

@@ -16,6 +16,7 @@ class _LoginPageState extends State<LoginPage> {
   final _password = TextEditingController();
   bool _busy = false;
   String? _error;
+  bool _obscurePassword = true;
 
   Future<void> _login() async {
     setState(() {
@@ -43,28 +44,43 @@ class _LoginPageState extends State<LoginPage> {
     body: SafeArea(
       child: Center(
         child: SingleChildScrollView(
-          padding: const EdgeInsets.all(24),
+          padding: const EdgeInsets.fromLTRB(24, 32, 24, 24),
           child: ConstrainedBox(
             constraints: const BoxConstraints(maxWidth: 420),
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.stretch,
               children: [
-                Icon(
-                  Icons.engineering_rounded,
-                  size: 72,
-                  color: Theme.of(context).colorScheme.primary,
+                Align(
+                  child: Container(
+                    width: 72,
+                    height: 72,
+                    decoration: BoxDecoration(
+                      color: Theme.of(context).colorScheme.primaryContainer,
+                      borderRadius: BorderRadius.circular(24),
+                    ),
+                    child: Icon(
+                      Icons.engineering_rounded,
+                      size: 38,
+                      color: Theme.of(context).colorScheme.primary,
+                      semanticLabel: '服务工作台标识',
+                    ),
+                  ),
                 ),
-                const SizedBox(height: 20),
+                const SizedBox(height: 24),
                 Text(
                   '瓶安芯服务工作台',
                   textAlign: TextAlign.center,
-                  style: Theme.of(
-                    context,
-                  ).textTheme.headlineMedium?.copyWith(fontWeight: FontWeight.w900),
+                  style: Theme.of(context).textTheme.headlineMedium,
                 ),
                 const SizedBox(height: 8),
-                const Text('配送、安装维修与安检共用入口', textAlign: TextAlign.center),
-                const SizedBox(height: 34),
+                Text(
+                  '配送、安装维修与安检共用入口',
+                  textAlign: TextAlign.center,
+                  style: Theme.of(context).textTheme.bodyLarge?.copyWith(
+                    color: Theme.of(context).colorScheme.onSurfaceVariant,
+                  ),
+                ),
+                const SizedBox(height: 40),
                 TextField(
                   controller: _phone,
                   keyboardType: TextInputType.phone,
@@ -76,22 +92,50 @@ class _LoginPageState extends State<LoginPage> {
                 const SizedBox(height: 14),
                 TextField(
                   controller: _password,
-                  obscureText: true,
-                  decoration: const InputDecoration(
+                  obscureText: _obscurePassword,
+                  autofillHints: const [AutofillHints.password],
+                  decoration: InputDecoration(
                     labelText: '登录密码',
-                    prefixIcon: Icon(Icons.lock_outline),
+                    prefixIcon: const Icon(Icons.lock_outline),
+                    suffixIcon: IconButton(
+                      tooltip: _obscurePassword ? '显示密码' : '隐藏密码',
+                      onPressed: () => setState(() => _obscurePassword = !_obscurePassword),
+                      icon: Icon(
+                        _obscurePassword
+                            ? Icons.visibility_outlined
+                            : Icons.visibility_off_outlined,
+                      ),
+                    ),
                   ),
                 ),
                 if (_error != null)
                   Padding(
                     padding: const EdgeInsets.only(top: 12),
-                    child: Text(
-                      _error!,
-                      style: TextStyle(color: Theme.of(context).colorScheme.error),
+                    child: Semantics(
+                      liveRegion: true,
+                      child: Row(
+                        crossAxisAlignment: CrossAxisAlignment.start,
+                        children: [
+                          Icon(
+                            Icons.error_outline,
+                            size: 20,
+                            color: Theme.of(context).colorScheme.error,
+                          ),
+                          const SizedBox(width: 8),
+                          Expanded(
+                            child: Text(
+                              _error!,
+                              style: Theme.of(context).textTheme.bodyMedium?.copyWith(
+                                color: Theme.of(context).colorScheme.error,
+                              ),
+                            ),
+                          ),
+                        ],
+                      ),
                     ),
                   ),
-                const SizedBox(height: 20),
-                ElevatedButton(
+                const SizedBox(height: 24),
+                FilledButton(
                   onPressed: _busy ? null : _login,
                   child: _busy
                       ? const SizedBox.square(
@@ -100,11 +144,13 @@ class _LoginPageState extends State<LoginPage> {
                         )
                       : const Text('进入工作台'),
                 ),
-                const SizedBox(height: 12),
-                const Text(
+                const SizedBox(height: 16),
+                Text(
                   '账号与角色由平台审核分配，不提供自助注册',
                   textAlign: TextAlign.center,
-                  style: TextStyle(fontSize: 12),
+                  style: Theme.of(context).textTheme.labelSmall?.copyWith(
+                    color: Theme.of(context).colorScheme.onSurfaceVariant,
+                  ),
                 ),
               ],
             ),