merge: 合并 main 分支到 test，解决 config 和 modelWhitelist 冲突

- config.go: 保留 Sora 配置，合入 SubscriptionCache 配置
- useModelWhitelist.ts: 同时保留 soraModels 和 antigravityModels

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/internal/service/gemini_multiplatform_test.go

@@ -268,6 +268,22 @@ func (m *mockGatewayCacheForGemini) DeleteSessionAccountID(ctx context.Context,
 	return nil
 }
 
+func (m *mockGatewayCacheForGemini) IncrModelCallCount(ctx context.Context, accountID int64, model string) (int64, error) {
+	return 0, nil
+}
+
+func (m *mockGatewayCacheForGemini) GetModelLoadBatch(ctx context.Context, accountIDs []int64, model string) (map[int64]*ModelLoadInfo, error) {
+	return nil, nil
+}
+
+func (m *mockGatewayCacheForGemini) FindGeminiSession(ctx context.Context, groupID int64, prefixHash, digestChain string) (uuid string, accountID int64, found bool) {
+	return "", 0, false
+}
+
+func (m *mockGatewayCacheForGemini) SaveGeminiSession(ctx context.Context, groupID int64, prefixHash, digestChain, uuid string, accountID int64) error {
+	return nil
+}
+
 // TestGeminiMessagesCompatService_SelectAccountForModelWithExclusions_GeminiPlatform 测试 Gemini 单平台选择
 func TestGeminiMessagesCompatService_SelectAccountForModelWithExclusions_GeminiPlatform(t *testing.T) {
 	ctx := context.Background()
@@ -883,7 +899,7 @@ func TestGeminiMessagesCompatService_isModelSupportedByAccount(t *testing.T) {
 		{
 			name:     "Antigravity平台-支持claude模型",
 			account:  &Account{Platform: PlatformAntigravity},
-			model:    "claude-3-5-sonnet-20241022",
+			model:    "claude-sonnet-4-5",
 			expected: true,
 		},
 		{
@@ -892,6 +908,39 @@ func TestGeminiMessagesCompatService_isModelSupportedByAccount(t *testing.T) {
 			model:    "gpt-4",
 			expected: false,
 		},
+		{
+			name:     "Antigravity平台-空模型允许",
+			account:  &Account{Platform: PlatformAntigravity},
+			model:    "",
+			expected: true,
+		},
+		{
+			name: "Antigravity平台-自定义映射-支持自定义模型",
+			account: &Account{
+				Platform: PlatformAntigravity,
+				Credentials: map[string]any{
+					"model_mapping": map[string]any{
+						"my-custom-model": "upstream-model",
+						"gpt-4o":          "some-model",
+					},
+				},
+			},
+			model:    "my-custom-model",
+			expected: true,
+		},
+		{
+			name: "Antigravity平台-自定义映射-不在映射中的模型不支持",
+			account: &Account{
+				Platform: PlatformAntigravity,
+				Credentials: map[string]any{
+					"model_mapping": map[string]any{
+						"my-custom-model": "upstream-model",
+					},
+				},
+			},
+			model:    "claude-sonnet-4-5",
+			expected: false,
+		},
 		{
 			name:     "Gemini平台-无映射配置-支持所有模型",
 			account:  &Account{Platform: PlatformGemini},