feat: 球队实体一致性 — 归一化咽喉 + team_aliases 别名机制

events/standings 创建 Team 前均经 team_names.normalize(已有,确认),
TeamRepository.get_or_create 收敛为归一化唯一咽喉 + info 日志。

新增 team_aliases 表(NFKD 归一别名 → teams.id FK CASCADE),
定位三步链:normalize(name) → teams.name → team_aliases → insert。
不自动合并历史重复队;提供 POST /api/v1/admin/teams/aliases 显式添加。

迁移 0020_team_aliases + Admin 别名管理端点(admin_teams.py)。
全量测试 270 通过。

src/db/repositories.py

@@ -114,24 +114,59 @@ class TeamRepository:
     async def get_or_create(self, name: str, *, name_zh: str | None = None) -> Team:
         """按名获取球队,不存在则创建(name_zh 供 bzzoiro 管线写中文名)。
 
-        归一化咽喉:所有入库 Team.name 必须经过 team_names.normalize,
-        此处统一收敛,避免各调用点散落归一化逻辑导致重复 Team。
+        归一化咽喉 + 别名查找,三步定位:
+          1) normalize(name) → 查 teams.name
+          2) 查 team_aliases(以 normalize(name) 为幂等键)→ 复用已映射的 teams.id
+          3) 都没有 → insert 新 Team(归一名)
         创建新 Team 时 info 打出原始名与归一后的规范名,便于排查重名。
+        不自动合并历史重复队;需显式添加别名。
         """
         from src.data.team_names import normalize as normalize_name
+        from src.db.models import TeamAlias
 
         normalized = normalize_name(name) or name.strip()
+
+        # 1) 归一名直查 teams
         team = await self.get_by_name(normalized)
-        if team is None:
-            logger.info(
-                "创建新 Team: %s -> %s",
-                name, normalized,
-            )
-            team = Team(name=normalized, name_zh=name_zh)
-            self._session.add(team)
-            await self._session.flush()
+        if team is not None:
+            return team
+
+        # 2) 别名查找:normalize(别名) 作为幂等键,命中即复用已有 Team
+        alias = await self._session.get(TeamAlias, normalized)
+        if alias is not None:
+            team = await self._session.get(Team, alias.team_id)
+            if team is not None:
+                logger.info("Team 别名命中: %s -> %s(已有 id=%s)", name, normalized, team.id)
+                return team
+
+        # 3) 新建 Team(归一名)
+        logger.info("创建新 Team: %s -> %s", name, normalized)
+        team = Team(name=normalized, name_zh=name_zh)
+        self._session.add(team)
+        await self._session.flush()
         return team
 
+    async def add_alias(self, alias: str, team_id: int) -> TeamAlias:
+        """为已有 Team 添加别名。
+
+        幂等:以 normalize(alias) 为 PK,重复添加同一别名会 upsert。
+        不自动合并历史重复队,仅建立别名映射。
+        """
+        from src.data.team_names import normalize as normalize_name
+        from src.db.models import TeamAlias
+
+        normalized = normalize_name(alias) or alias.strip()
+        existing = await self._session.get(TeamAlias, normalized)
+        if existing is not None:
+            existing.team_id = team_id  # 允许重新指向
+            existing.original_alias = alias
+            await self._session.flush()
+            return existing
+        row = TeamAlias(alias_normalized=normalized, team_id=team_id, original_alias=alias)
+        self._session.add(row)
+        await self._session.flush()
+        return row
+
     async def get_all_by_names(self, names: list[str]) -> dict[str, Team]:
         """批量获取球队,返回 name → Team 映射。"""
         if not names: