refactor: 调度器迁移至独立模块，消除 services->api 反向依赖

- 将调度器相关模块从 src/services/cache/ 迁移到 src/services/scheduling/
- 下沉类型定义到 core 层: AccessRestrictions, ProviderAuthInfo, ParsedChunk/StreamStats, 视频工具函数
- 提取 thinking_cache 签名缓存到 core/api_format/conversion/
- 提取 provider 认证逻辑到 services/provider/auth
- 提取遥测记录到 services/usage/telemetry
- 提取 models 列表缓存到 services/cache/model_list_cache
- 更新所有引用方的 import 路径及相关测试

src/api/public/gemini_files.py

@@ -36,9 +36,9 @@ from src.core.logger import logger
 from src.database import create_session
 from src.models.database import ApiKey, GlobalModel, Model, Provider, ProviderEndpoint, User
 from src.services.auth.service import AuthService
-from src.services.cache.aware_scheduler import CacheAwareScheduler, ProviderCandidate
 from src.services.gemini_files_mapping import delete_file_key_mapping, store_file_key_mapping
 from src.services.provider.transport import redact_url_for_log
+from src.services.scheduling.aware_scheduler import CacheAwareScheduler, ProviderCandidate
 
 
 @dataclass