feat(backend): Phase 1 数据层 — Domain / Provider / Failover 审计 + 持久化 + 同步 CLI

- domain：市场数据实体（Stock / 交易日历 / 日线 / 复权 / 财务含 announce_date）+ Repository 与 MarketDataProvider Protocol
- 数据源：TushareProvider（归一化、重试、鉴权错误归类）、SinaProvider（备用，明确前复权口径与能力边界）、FailoverProvider + SyncLog 审计（禁止静默切换）
- 持久化：SQLAlchemy 2.x Models + Repository 实现（按业务键幂等 upsert、as_of_date 防未来函数过滤）+ Alembic 迁移
- CLI：uv run python -m app.cli.sync {basic|calendar|daily|financial|verify}，支持 --resume 断点续传
- 真实 Tushare 验证：stock 5556 / 交易日历 366 / daily+factor 242 / 财务 55；sync_log 审计完整
- 测试：38 passed（domain / provider / failover / repository / 未来函数 / 迁移），ruff clean

backend/app/domain/repositories/market.py

@@ -0,0 +1,70 @@
+"""Repository Protocol（Phase 1 数据层）。
+
+业务层只依赖这些 Protocol；具体实现位于 infrastructure/persistence。
+实体一律以 domain.entities 类型进出，禁止把 ORM Model 泄漏到上层。
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+from datetime import date
+from typing import Protocol
+
+from app.domain.entities.market import (
+    AdjustFactor,
+    DailyBar,
+    FinancialIndicator,
+    Stock,
+    SyncLog,
+    TradingCalendar,
+)
+
+
+class StockRepository(Protocol):
+    def get_by_symbol(self, symbol: str) -> Stock | None: ...
+
+    def list(self) -> list[Stock]: ...
+
+    def upsert_many(self, stocks: Sequence[Stock]) -> int:
+        """批量写入，以 symbol 为幂等键，返回写入/更新的行数。"""
+
+
+class TradingCalendarRepository(Protocol):
+    def upsert_many(self, days: Sequence[TradingCalendar]) -> int: ...
+
+    def list_range(self, start: date, end: date) -> list[TradingCalendar]: ...
+
+    def is_open(self, day: date) -> bool: ...
+
+
+class DailyBarRepository(Protocol):
+    def upsert_many(self, bars: Sequence[DailyBar]) -> int: ...
+
+    def get_range(self, symbol: str, start: date, end: date) -> list[DailyBar]: ...
+
+    def latest_date(self, symbol: str) -> date | None:
+        """断点续传用：该股票本地已有数据的最新交易日。"""
+
+
+class AdjustFactorRepository(Protocol):
+    def upsert_many(self, factors: Sequence[AdjustFactor]) -> int: ...
+
+    def get_range(self, symbol: str, start: date, end: date) -> list[AdjustFactor]: ...
+
+
+class FinancialRepository(Protocol):
+    def upsert_many(self, rows: Sequence[FinancialIndicator]) -> int: ...
+
+    def list_announced(
+        self,
+        symbol: str,
+        as_of_date: date,
+        report_start: date | None = None,
+    ) -> list[FinancialIndicator]:
+        """只返回 announce_date <= as_of_date 的记录 —— 未来函数红线。"""
+
+
+class SyncLogRepository(Protocol):
+    def add(self, log: SyncLog) -> SyncLog: ...
+
+    def recent(self, source: str | None = None, limit: int = 20) -> list[SyncLog]: ...