feat(trader): 科创板200股最小手数(分期项切片)—lot_size_for+matcher板块取整

科创板(688/689)最小200股1股递增(不整倍); 主板/创业/北交100整倍; 卖出不取整。
- limit.py 加 lot_size_for(symbol)
- matcher cross_order 买入取整按板块(star≥200不取整, 其余100整倍)
- routes_paper cta size=lot_size_for(symbol)
- test: 688981 买150拒/买250不取整; 主板用例不变; 63/63通过

tests/trader/test_matcher.py

@@ -174,6 +174,29 @@ def test_sell_odd_lot_allowed():
     assert isinstance(t, PaperTrade) and t.volume == 50
 
 
+# ---- 科创板 200 股最小手数（分期项）----
+def test_star_buy_below_200_rejected():
+    """科创板 688981 买 150 股 < 200 → 拒单（200 股起）。"""
+    r = cross_order(
+        PaperOrder("s1", "688981", OrderSide.BUY, 0, 150, True),
+        mkbar(10, 10, 10, 10),
+        PREV,
+        CFG,
+    )
+    assert isinstance(r, PaperReject) and r.reason == "volume_below_min_lot"
+
+
+def test_star_buy_250_not_rounded_to_200():
+    """科创板 688981 买 250 股 → ≥200，1 股递增不取整，成交 250（非主板 100 整倍）。"""
+    t = cross_order(
+        PaperOrder("s1", "688981", OrderSide.BUY, 0, 250, True),
+        mkbar(10, 10, 10, 10),
+        PREV,
+        CFG,
+    )
+    assert isinstance(t, PaperTrade) and t.volume == 250
+
+
 # ---- 费用 ----
 def test_commission_uses_min_5_yuan():
     # 100 股 × 10 元 × 0.0003 = 0.3 → 不足 5 元，收 5