博弈分析按合约分类展示，新增合约下拉选择器

ft-app/app/seed.py

@@ -262,8 +262,9 @@ def seed():
 
         # --- Seed position snapshots ---
         existing_pos = {
-            (r.institution, r.direction, r.date)
+            (r.contract_code, r.institution, r.direction, r.date)
             for r in db.query(
+                PositionSnapshot.contract_code,
                 PositionSnapshot.institution,
                 PositionSnapshot.direction,
                 PositionSnapshot.date,
@@ -273,9 +274,10 @@ def seed():
         snaps = []
         for inst, direction, date_str, pos, delta, cost in POSITION_DATA_SHORT:
             d = date.fromisoformat(date_str)
-            if (inst, direction, d) not in existing_pos:
+            if ("FG2609", inst, direction, d) not in existing_pos:
                 snaps.append(
                     PositionSnapshot(
+                        contract_code="FG2609",
                         institution=inst,
                         direction=direction,
                         date=d,