feat(selection): M6.3 选股结果落库 + /api/selections（快照 + 逐候选行）

- domain/repositories/selection.py + SelectionMeta：选股 Repository Protocol
- models/selection.py + migration a6c91d4e7f20：selection_snapshot（查询/统计快照）+
  selection_result（逐候选：rank/score/factor_values/filter_status/reason JSON）
- repositories/selection_impl.py：save/get/list_recent（读回重建 SelectionResult）
- api/selections.py：POST /api/selections（同步执行+落库，返回 selection_id+result）、
  GET /{id}、GET 列表（as_of/method 过滤）；deps 装配 SelectionService/Repo
- config._build_mysql_url：仅编码破坏 URL 结构的字符（修 Alembic configparser 遇 %21 崩）
- 迁移已在 MySQL 应用（alembic head a6c91d4e7f20）；tests/test_selections_api.py 4 例
  提交→读回一致/404/列表过滤/condition；全量 pytest 通过

backend/app/api/deps.py

@@ -10,15 +10,22 @@ from typing import Annotated
 from fastapi import Depends
 from sqlalchemy.orm import Session
 
+from app.application.services.selection_service import SelectionService
 from app.domain.repositories.jobs import ExperimentRepository, JobRepository
 from app.domain.repositories.market import (
     DailyBarRepository,
+    FinancialRepository,
     StockRepository,
 )
+from app.domain.repositories.selection import SelectionRepository
 from app.infrastructure.persistence.sqlalchemy.repositories.market_impl import (
     SqlAlchemyDailyBarRepository,
+    SqlAlchemyFinancialRepository,
     SqlAlchemyStockRepository,
 )
+from app.infrastructure.persistence.sqlalchemy.repositories.selection_impl import (
+    SqlAlchemySelectionRepository,
+)
 from app.infrastructure.persistence.sqlalchemy.session import get_session
 from app.quant.engine import LocalEngine, QuantEngine
 from app.quant.service import ResearchService
@@ -34,6 +41,10 @@ def _daily_repo_factory(session: DbSession) -> DailyBarRepository:
     return SqlAlchemyDailyBarRepository(session)
 
 
+def _financial_repo_factory(session: DbSession) -> FinancialRepository:
+    return SqlAlchemyFinancialRepository(session)
+
+
 def _engine_factory() -> QuantEngine:
     return LocalEngine()
 
@@ -46,10 +57,25 @@ def _service_factory(
     return ResearchService(stock_repo, daily_repo, engine)
 
 
+def _selection_service_factory(
+    stock_repo: Annotated[StockRepository, Depends(_stock_repo_factory)],
+    daily_repo: Annotated[DailyBarRepository, Depends(_daily_repo_factory)],
+    financial_repo: Annotated[FinancialRepository, Depends(_financial_repo_factory)],
+) -> SelectionService:
+    
+    return SelectionService(stock_repo, daily_repo, financial_repo)
+
+
+def _selection_repo_factory(session: DbSession) -> SelectionRepository:
+    return SqlAlchemySelectionRepository(session)
+
+
 StockRepoDep = Annotated[StockRepository, Depends(_stock_repo_factory)]
 DailyRepoDep = Annotated[DailyBarRepository, Depends(_daily_repo_factory)]
 EngineDep = Annotated[QuantEngine, Depends(_engine_factory)]
 ResearchServiceDep = Annotated[ResearchService, Depends(_service_factory)]
+SelectionServiceDep = Annotated[SelectionService, Depends(_selection_service_factory)]
+SelectionRepoDep = Annotated[SelectionRepository, Depends(_selection_repo_factory)]
 
 
 def _job_repo_factory(session: DbSession):