fix: 配额系统添加 pro 套餐并支持未知套餐 fallback 到 free

- 在 QUOTA_TIERS 中添加 pro 套餐，配额与 premium 相同
- QuotaRegistry.get_tier() 对未知套餐 fallback 到 free 而非返回 None
- QuotaRegistry.get_limit() 同步更新 fallback 逻辑
- 更新所有相关单元测试以匹配新行为
- 新增 TestProTier 测试类验证 pro 套餐正确性

修复问题：用户 subscription_plan='pro' 时所有配额 limit=0 导致创建操作被拦截

packages/domain/quota.py

@@ -1,9 +1,10 @@
 """Quota system with registry pattern.
 
-Three subscription tiers with different limits:
+Four subscription tiers with different limits:
 - free:    2GB storage, 5 videos/month, 3 concurrent, 3 templates, 50 titles, 10 voiceovers, no AI voice
 - basic:   20GB storage, 30 videos/month, 10 concurrent, 15 templates, 500 titles, 100 voiceovers, AI voice
 - premium: 100GB storage, 100 videos/month, 20 concurrent, unlimited templates, 500 titles, 100 voiceovers, AI voice
+- pro:     Same as premium (alias for premium tier)
 
 Quota dimensions are registered by modules via the ModuleRegistry,
 and checked against the user's subscription plan.
@@ -99,6 +100,22 @@ QUOTA_TIERS: Dict[str, QuotaTier] = {
             QuotaDimension.DEDUP_REPORT_ENABLED: 1,
         },
     ),
+    "pro": QuotaTier(
+        name="pro",
+        limits={
+            QuotaDimension.STORAGE_GB: 100,
+            QuotaDimension.VIDEOS_PER_MONTH: 100,
+            QuotaDimension.MAX_CONCURRENT: 20,
+            QuotaDimension.MAX_TEMPLATES: float("inf"),  # 不限量
+            QuotaDimension.MAX_TITLES: 500,
+            QuotaDimension.MAX_VOICEOVERS: 100,
+            QuotaDimension.AI_VOICE_ENABLED: 1,
+            QuotaDimension.AI_VOICE_CREDITS: 500,
+            QuotaDimension.BATCH_EXPORT_ENABLED: 1,
+            QuotaDimension.MULTI_PLATFORM_ENABLED: 1,
+            QuotaDimension.DEDUP_REPORT_ENABLED: 1,
+        },
+    ),
 }
 
 
@@ -174,15 +191,13 @@ class QuotaRegistry:
             for tier in self._tiers.values():
                 tier.limits.setdefault(dimension, 0)
 
-    def get_tier(self, plan_name: str) -> Optional[QuotaTier]:
-        """获取套餐配额定义"""
-        return self._tiers.get(plan_name)
+    def get_tier(self, plan_name: str) -> QuotaTier:
+        """获取套餐配额定义，未知套餐 fallback 到 free"""
+        return self._tiers.get(plan_name, self._tiers["free"])
 
     def get_limit(self, plan_name: str, dimension: str) -> float:
-        """获取指定套餐在指定维度的限制"""
-        tier = self._tiers.get(plan_name)
-        if tier is None:
-            return 0
+        """获取指定套餐在指定维度的限制，未知套餐 fallback 到 free"""
+        tier = self._tiers.get(plan_name, self._tiers["free"])
         return tier.get_limit(dimension)
 
     def list_dimensions(self) -> Dict[str, str]:

tests/unit/domain/test_quota.py

@@ -354,13 +354,13 @@ class TestQuotaRegistry:
         assert len(reg.list_dimensions()) == len(QuotaDimension)
 
     def test_list_tiers(self):
-        """三个套餐等级."""
+        """四个套餐等级."""
         reg = QuotaRegistry()
         tiers = reg.list_tiers()
+        assert "pro" in tiers
         assert "free" in tiers
         assert "basic" in tiers
-        assert "premium" in tiers
-        assert len(tiers) == 3
+        assert len(tiers) == 4
 
     def test_get_tier_existing(self):
         """获取已有的套餐."""
@@ -370,9 +370,11 @@ class TestQuotaRegistry:
         assert tier.name == "free"
 
     def test_get_tier_nonexistent(self):
-        """获取不存在的套餐返回 None."""
+        """不存在的套餐 fallback 到 free"""
         reg = QuotaRegistry()
-        assert reg.get_tier("enterprise") is None
+        tier = reg.get_tier("enterprise")
+        assert tier is not None
+        assert tier.name == "free"
 
     def test_get_limit_existing(self):
         """获取已有限制."""
@@ -380,9 +382,9 @@ class TestQuotaRegistry:
         assert reg.get_limit("free", QuotaDimension.STORAGE_GB) == 2
 
     def test_get_limit_nonexistent_plan(self):
-        """不存在的套餐返回 0."""
+        """不存在的套餐 fallback 到 free 配额"""
         reg = QuotaRegistry()
-        assert reg.get_limit("enterprise", QuotaDimension.STORAGE_GB) == 0
+        assert reg.get_limit("enterprise", QuotaDimension.STORAGE_GB) == 2  # fallback to free
 
     def test_get_limit_unknown_dimension(self):
         """未知维度返回 0."""
@@ -506,12 +508,12 @@ class TestQuotaChecker:
         assert result.usage_percent == 0.0
 
     def test_check_unknown_plan(self):
-        """未知套餐，限制为0."""
+        """未知套餐 fallback 到 free"""
         checker = QuotaChecker()
         result = checker.check("enterprise", QuotaDimension.STORAGE_GB, 0)
-        assert result.limit == 0
+        assert result.limit == 2  # fallback to free tier, storage_gb=2
         # used=0, limit=0 → 0 < 0 is False → allowed=False
-        assert result.allowed is False
+        assert result.allowed is True  # used=0, limit=2, allowed
         assert result.warning_level == QuotaWarningLevel.NORMAL
 
     def test_check_unknown_dimension(self):

tests/unit/test_quota.py

@@ -222,7 +222,7 @@ class TestQuotaRegistry:
 
     def test_get_limit_unknown_plan_returns_zero(self):
         reg = QuotaRegistry()
-        assert reg.get_limit("unknown_plan", "storage_gb") == 0
+        assert reg.get_limit("unknown_plan", "storage_gb") == 2  # fallback to free
 
     def test_get_tier_free(self):
         reg = QuotaRegistry()
@@ -231,8 +231,11 @@ class TestQuotaRegistry:
         assert tier.name == "free"
 
     def test_get_tier_unknown_returns_none(self):
+        """未知套餐 fallback 到 free"""
         reg = QuotaRegistry()
-        assert reg.get_tier("nonexistent") is None
+        tier = reg.get_tier("nonexistent")
+        assert tier is not None
+        assert tier.name == "free"
 
     def test_register_new_dimension(self):
         reg = QuotaRegistry()
@@ -300,8 +303,8 @@ class TestQuotaChecker:
     def test_check_unknown_plan(self):
         checker = QuotaChecker()
         result = checker.check("unknown", "storage_gb", 1.0)
-        assert result.allowed is False
-        assert result.limit == 0
+        assert result.allowed is True  # fallback to free, limit=2, used=1.0 < 2
+        assert result.limit == 2  # fallback to free tier
 
     def test_check_multiple(self):
         checker = QuotaChecker()
@@ -412,3 +415,28 @@ class TestGlobalSingletons:
         result = quota_checker.check("free", "storage_gb", 1.0)
         assert result.allowed is True
         assert result.limit == 2
+
+
+class TestProTier:
+    """Pro 套餐专项测试"""
+
+    def test_pro_tier_exists(self):
+        """pro 套餐存在于 QUOTA_TIERS"""
+        from packages.domain.quota import QUOTA_TIERS
+        assert "pro" in QUOTA_TIERS
+
+    def test_pro_tier_same_as_premium(self):
+        """pro 套餐配额与 premium 完全一致"""
+        from packages.domain.quota import QUOTA_TIERS
+        pro = QUOTA_TIERS["pro"]
+        premium = QUOTA_TIERS["premium"]
+        assert pro.limits == premium.limits
+
+    def test_pro_tier_get_limit(self):
+        """pro 套餐各维度配额正确"""
+        reg = QuotaRegistry()
+        assert reg.get_limit("pro", "storage_gb") == 100
+        assert reg.get_limit("pro", "videos_per_month") == 100
+        assert reg.get_limit("pro", "max_concurrent") == 20
+        assert reg.get_limit("pro", "max_titles") == 500
+        assert reg.get_limit("pro", "ai_voice_enabled") == 1

tests/unit/test_quota_domain.py

@@ -185,9 +185,10 @@ class TestQuotaRegistry:
         reg = QuotaRegistry()
         tiers = reg.list_tiers()
         assert "free" in tiers
+        assert "pro" in tiers
         assert "basic" in tiers
         assert "premium" in tiers
-        assert len(tiers) == 3
+        assert len(tiers) == 4
 
     def test_get_tier_existing(self):
         reg = QuotaRegistry()
@@ -197,7 +198,9 @@ class TestQuotaRegistry:
 
     def test_get_tier_unknown(self):
         reg = QuotaRegistry()
-        assert reg.get_tier("unknown_plan") is None
+        tier = reg.get_tier("unknown_plan")
+        assert tier is not None
+        assert tier.name == "free"
 
     def test_get_limit_known(self):
         reg = QuotaRegistry()
@@ -206,7 +209,7 @@ class TestQuotaRegistry:
 
     def test_get_limit_unknown_plan(self):
         reg = QuotaRegistry()
-        assert reg.get_limit("unknown", "storage_gb") == 0
+        assert reg.get_limit("unknown", "storage_gb") == 2  # fallback to free tier
 
     def test_register_new_dimension(self):
         reg = QuotaRegistry()