feat: ¥1 首月特惠套餐（新店专享，每店限购一次，官网+App 同步上线）

- 后端：payPlans 新增 promo_first_month（¥1/30 天/标准版权益）；下单强校验每店限购一次（仅 paid 计数，弃单可重下），已享用返回 409；新增 GET /license/promo-status 供前端置灰
- 官网：checkout 套餐段第二位插「🔥 首月特惠 ¥1」+ 推广横幅 + 划线原价 ¥299；首页价格区第二位插特惠卡（5 列）；已享用自动置灰
- App：购买弹窗套餐段改三档（标准/特惠/高级），特惠选中显示推广横幅与划线价，已享用置灰并禁用提交
- 实付金额以 pay 侧为准，pay 需 seed promo_first_month 产品后生效

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JJ1g8XV1YhhmHRzhwWEW7o

client/lib/core/config/license_plans.dart

@@ -23,6 +23,17 @@ class LicensePlanGroup {
 }
 
 class LicensePlans {
+  /// 新店首月特惠：¥1 体验 30 天标准版全部功能，每个门店限购一次
+  /// （服务端强校验，前端据 GET /license/promo-status 置灰）。
+  static const promo = LicensePlan('promo_first_month', 1, 30);
+  static const promoOriginalPrice = 299; // 划线原价（=标准版月付）
+  static const promoFeats = [
+    '标准版全部功能，一分不少',
+    '单门店 · 单仓库 · 2 台客户端',
+    '1,000 张商品图片分享',
+    '每个门店限购一次',
+  ];
+
   static const standard = LicensePlanGroup(
     name: '标准版',
     feats: ['单门店 · 单仓库', '2 台客户端同时使用', '1,000 张商品图片分享'],

client/lib/repositories/license_repository.dart

@@ -68,6 +68,18 @@ class LicenseRepository {
     }
   }
 
+  /// 本店首月特惠是否已享用（购买弹窗据此置灰特惠档）。
+  Future<bool> promoUsed() async {
+    try {
+      final resp = await _client.get('/license/promo-status');
+      final data = resp.data['data'] as Map<String, dynamic>?;
+      return data?['used'] as bool? ?? false;
+    } on DioException {
+      // 查询失败不阻塞弹窗：按未享用展示，下单时服务端仍会强校验
+      return false;
+    }
+  }
+
   /// Deactivate (unbind) this device from its license.
   Future<void> deactivate() async {
     final deviceId = await DeviceId.get();

client/lib/screens/settings/purchase_dialog.dart

@@ -42,19 +42,32 @@ class _PurchaseDialog extends ConsumerStatefulWidget {
 
 class _PurchaseDialogState extends ConsumerState<_PurchaseDialog> {
   _Phase _phase = _Phase.pick;
-  int _groupIdx = 0; // 0=标准版 1=高级版
+  int _tabIdx = 0; // 0=标准版 1=首月特惠 2=高级版
   int _cycleIdx = 0; // 0=年付 1=月付
   bool _submitting = false;
   bool _checking = false;
+  bool _promoUsed = false; // 首月特惠每店限一次，已享用则置灰（服务端仍强校验）
 
   PurchaseOrder? _order;
   DateTime? _newExpiresAt;
   Timer? _pollTimer;
 
-  LicensePlanGroup get _group => LicensePlans.groups[_groupIdx];
-  LicensePlan get _plan => _cycleIdx == 0 ? _group.annual : _group.monthly;
+  bool get _isPromo => _tabIdx == 1;
+  LicensePlanGroup get _group =>
+      _tabIdx == 0 ? LicensePlans.standard : LicensePlans.pro;
+  LicensePlan get _plan => _isPromo
+      ? LicensePlans.promo
+      : (_cycleIdx == 0 ? _group.annual : _group.monthly);
   String get _cycleLabel => _cycleIdx == 0 ? '年付' : '月付';
 
+  @override
+  void initState() {
+    super.initState();
+    ref.read(licenseRepositoryProvider).promoUsed().then((used) {
+      if (mounted && used) setState(() => _promoUsed = true);
+    });
+  }
+
   @override
   void dispose() {
     _pollTimer?.cancel();
@@ -133,9 +146,15 @@ class _PurchaseDialogState extends ConsumerState<_PurchaseDialog> {
             DsButton('取消',
                 onPressed:
                     _submitting ? null : () => Navigator.of(context).pop()),
-            DsButton(_submitting ? '正在创建订单…' : '提交订单 · ¥${_fmt(_plan.price)}',
+            DsButton(
+                _submitting
+                    ? '正在创建订单…'
+                    : _isPromo && _promoUsed
+                        ? '本店已享受过'
+                        : '提交订单 · ¥${_fmt(_plan.price)}',
                 variant: DsBtnVariant.primary,
-                onPressed: _submitting ? null : _submit),
+                onPressed:
+                    _submitting || (_isPromo && _promoUsed) ? null : _submit),
           ],
         _Phase.waiting => [
             DsButton('稍后再说', onPressed: () => Navigator.of(context).pop()),
@@ -153,24 +172,60 @@ class _PurchaseDialogState extends ConsumerState<_PurchaseDialog> {
   }
 
   Widget _buildPick(AppTokens t) {
+    final promoGrayed = _isPromo && _promoUsed;
+    final feats = _isPromo ? LicensePlans.promoFeats : _group.feats;
     return Column(
       mainAxisSize: MainAxisSize.min,
       crossAxisAlignment: CrossAxisAlignment.start,
       children: [
-        Row(children: [
+        Wrap(spacing: 10, runSpacing: 8, children: [
           DsSeg(
-            items: [for (final g in LicensePlans.groups) g.name],
-            index: _groupIdx,
-            onChanged: (i) => setState(() => _groupIdx = i),
-          ),
-          const SizedBox(width: 10),
-          DsSeg(
-            items: const ['年付', '月付'],
-            index: _cycleIdx,
-            onChanged: (i) => setState(() => _cycleIdx = i),
+            items: [
+              '标准版',
+              _promoUsed ? '首月特惠（已享受）' : '🔥 首月特惠 ¥1',
+              '高级版',
+            ],
+            index: _tabIdx,
+            onChanged: (i) => setState(() => _tabIdx = i),
           ),
+          if (!_isPromo)
+            DsSeg(
+              items: const ['年付', '月付'],
+              index: _cycleIdx,
+              onChanged: (i) => setState(() => _cycleIdx = i),
+            ),
         ]),
         const SizedBox(height: 14),
+        if (_isPromo) ...[
+          Container(
+            width: double.infinity,
+            padding: const EdgeInsets.all(12),
+            decoration: BoxDecoration(
+              color: promoGrayed ? t.bg : t.warnBg,
+              border: Border.all(color: promoGrayed ? t.border : t.warn),
+              borderRadius: BorderRadius.circular(AppDims.rMd),
+            ),
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Text(promoGrayed ? '本店已享受过首月特惠' : '新店专享 · 仅 ¥1 体验 30 天',
+                    style: TextStyle(
+                        fontSize: AppDims.fsBody,
+                        fontWeight: FontWeight.w700,
+                        color: promoGrayed ? t.faint : t.warn)),
+                const SizedBox(height: 3),
+                Text(
+                    promoGrayed
+                        ? '首月特惠每个门店限购一次，可选择标准版或高级版继续续费。'
+                        : '解锁标准版全部功能，原价 ¥299，每个门店限购一次——试过才知道多省心。',
+                    style: TextStyle(
+                        fontSize: AppDims.fsSm,
+                        color: promoGrayed ? t.faint : t.text)),
+              ],
+            ),
+          ),
+          const SizedBox(height: 10),
+        ],
         Container(
           width: double.infinity,
           padding: const EdgeInsets.all(14),
@@ -182,16 +237,18 @@ class _PurchaseDialogState extends ConsumerState<_PurchaseDialog> {
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
-              for (final f in _group.feats)
+              for (final f in feats)
                 Padding(
                   padding: const EdgeInsets.symmetric(vertical: 3),
                   child: Row(children: [
-                    Icon(LucideIcons.check, size: 14, color: t.success),
+                    Icon(LucideIcons.check,
+                        size: 14, color: promoGrayed ? t.faint : t.success),
                     const SizedBox(width: 8),
                     Expanded(
                         child: Text(f,
                             style: TextStyle(
-                                fontSize: AppDims.fsSm, color: t.text))),
+                                fontSize: AppDims.fsSm,
+                                color: promoGrayed ? t.faint : t.text))),
                   ]),
                 ),
             ],
@@ -202,14 +259,31 @@ class _PurchaseDialogState extends ConsumerState<_PurchaseDialog> {
           crossAxisAlignment: CrossAxisAlignment.end,
           children: [
             Expanded(
-              child: Text('${_group.name} · $_cycleLabel · ${_plan.days} 天授权',
+              child: Text(
+                  _isPromo
+                      ? '首月特惠 · ${_plan.days} 天授权'
+                      : '${_group.name} · $_cycleLabel · ${_plan.days} 天授权',
                   style: TextStyle(fontSize: AppDims.fsSm, color: t.muted)),
             ),
+            if (_isPromo) ...[
+              Text('¥${_fmt(LicensePlans.promoOriginalPrice)}',
+                  style: TextStyle(
+                      fontSize: AppDims.fsSm,
+                      color: t.faint,
+                      decoration: TextDecoration.lineThrough,
+                      fontFamily: AppFonts.mono,
+                      fontFamilyFallback: AppFonts.monoFallback)),
+              const SizedBox(width: 8),
+            ],
             Text('¥${_fmt(_plan.price)}',
                 style: TextStyle(
                     fontSize: 24,
                     fontWeight: FontWeight.w700,
-                    color: t.heading,
+                    color: promoGrayed
+                        ? t.faint
+                        : _isPromo
+                            ? t.warn
+                            : t.heading,
                     fontFamily: AppFonts.mono,
                     fontFamilyFallback: AppFonts.monoFallback)),
           ],