feat: add strategy set CRUD operations (API + CLI)

app/repositories/portfolio_repository.py

@@ -47,6 +47,10 @@ class PortfolioRepository(Protocol):
 
     def get_strategy_set(self, id: str) -> StrategySet | None: ...
 
+    def list_strategy_sets(self) -> list[StrategySet]: ...
+
+    def delete_strategy_set(self, id: str) -> None: ...
+
     def save(
         self,
         portfolio: Portfolio,

app/repositories/postgres.py

@@ -385,6 +385,34 @@ class PostgresPortfolioRepository:
             return None
         return StrategySet(id=row[0], name=row[1], config=row[2], nick=row[3], created_at=row[4])
 
+    def list_strategy_sets(self) -> list[StrategySet]:
+        self.ensure_schema()
+        with self._connect().cursor() as cur:
+            cur.execute(
+                "SELECT id, name, config, nick, created_at FROM strategy_sets ORDER BY created_at DESC"
+            )
+            rows = cur.fetchall()
+        return [StrategySet(id=row[0], name=row[1], config=row[2], nick=row[3], created_at=row[4]) for row in rows]
+
+    def delete_strategy_set(self, id: str) -> None:
+        self.ensure_schema()
+        with self._connect().cursor() as cur:
+            # 1. Check if this strategy set is referenced by any portfolio
+            cur.execute(
+                """
+                SELECT COUNT(*) FROM portfolios
+                WHERE active_strategy_id = %s
+                   OR avabile_strategies @> ARRAY[%s]
+                """,
+                (id, id),
+            )
+            count = cur.fetchone()[0]
+            if count > 0:
+                raise ValueError(f"Strategy set is in use by {count} portfolio(s) and cannot be deleted")
+            
+            # 2. If not in use, proceed with deletion
+            cur.execute("DELETE FROM strategy_sets WHERE id = %s", (id,))
+
     def save(
         self,
         portfolio: Portfolio,