feat: implement priority_weighted_plus_percent pricing algorithm

backend/app/services/website_client.py

@@ -65,12 +65,32 @@ def calculate_target_rate(values: list[Any], percent: Any = 0, algorithm: str =
         base = min(rates)
     elif algorithm == "max_plus_percent":
         base = max(rates)
+    elif algorithm == "priority_weighted_plus_percent":
+        rates_sorted = sorted(rates)
+        N = len(rates_sorted)
+        if N == 1:
+            base = rates_sorted[0]
+        else:
+            base = Decimal("0")
+            remaining = Decimal("1.0")
+            for i in range(N):
+                if i == N - 1:
+                    weight = remaining
+                else:
+                    weight = remaining * Decimal("0.85")
+                    remaining -= weight
+                base += rates_sorted[i] * weight
     else:
         raise WebsiteError(f"不支持的算法：{algorithm}")
     pct = Decimal(str(percent or 0))
     if pct < 0:
         raise WebsiteError("百分比不能为负数")
-    return (base * (Decimal("1") + pct / Decimal("100"))).quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
+    target_rate = (base * (Decimal("1") + pct / Decimal("100"))).quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
+    if algorithm == "priority_weighted_plus_percent":
+        min_rate = min(rates)
+        if target_rate < min_rate:
+            target_rate = min_rate
+    return target_rate
 
 
 def _unwrap_data(value: Any) -> Any: