feat(req-002): implement portfolio tagging and tag filters

tests/test_portfolio_ownership.py

@@ -35,6 +35,29 @@ class FakeRepo:
     def list_recent_trades(self, portfolio_id: str, limit: int = 5) -> list[LedgerEntry]:
         return []
 
+    def list_portfolios(
+        self,
+        *,
+        broker: str | None = None,
+        status: str | None = None,
+        owner_user_id: str | None = None,
+        include_tags: list[str] | None = None,
+        exclude_tags: list[str] | None = None,
+        match_mode: str | None = None,
+    ):
+        if owner_user_id is not None and self._portfolio.owner_user_id != owner_user_id:
+            return []
+        return [self._portfolio]
+
+    def add_tag(self, portfolio_id: str, *, tag: str):
+        raise NotImplementedError()
+
+    def list_tags(self, portfolio_id: str):
+        return []
+
+    def remove_tag(self, portfolio_id: str, *, tag: str) -> None:
+        raise NotImplementedError()
+
     def get_strategy_set(self, id: str):
         if id == self._strategy.id:
             return self._strategy