feat(规则): 支持同一事件多规则按条件区分并全部发送

Motivation:
止盈、止损等不同策略信号会映射到同一事件（如 trade.close），但原有唯一约束要求每个事件只能有一条规则，无法按策略区分处理。放开该约束后，同一事件可配置多条规则，通过规则条件与精确/通配优先级区分，命中条件的规则全部发送；同时将去重键从消息原文改为信号维度，避免同一信号因时间戳等无关字段差异被误判为重复。

Changes:

* 移除规则 source_id+event 的唯一约束，改为普通索引
* 事件匹配改为返回命中优先级内所有启用规则，并按 ID 逐条派发
* 通知服务遍历多条规则，按条件过滤后聚合发送渠道
* 去重键由消息 body 哈希改为策略/币种/周期/方向/价格信号维度哈希

internal/engine/event_match.go

@@ -11,18 +11,33 @@ import (
 // Exact event wins; otherwise glob patterns (* and ?) via path.Match.
 // Among globs, more literal characters win; ties go to the smaller ID.
 func PickEventRule(event string, rules []model.Rule) *model.Rule {
-	var exact *model.Rule
-	var best *model.Rule
+	picked := PickEventRules(event, rules)
+	if len(picked) == 0 {
+		return nil
+	}
+	best := &picked[0]
+	for i := range picked[1:] {
+		if picked[i+1].ID < best.ID {
+			best = &picked[i+1]
+		}
+	}
+	return best
+}
+
+// PickEventRules returns every enabled rule at the winning specificity.
+// All exact event matches win as a group; otherwise all globs that share
+// the highest literal-character score.
+func PickEventRules(event string, rules []model.Rule) []model.Rule {
+	var exact []model.Rule
+	var globs []model.Rule
 	bestScore := -1
 	for i := range rules {
-		r := &rules[i]
+		r := rules[i]
 		if r.Enabled == 0 {
 			continue
 		}
 		if r.Event == event {
-			if exact == nil || r.ID < exact.ID {
-				exact = r
-			}
+			exact = append(exact, r)
 			continue
 		}
 		if !strings.ContainsAny(r.Event, "*?") {
@@ -33,15 +48,19 @@ func PickEventRule(event string, rules []model.Rule) *model.Rule {
 			continue
 		}
 		score := globSpecificity(r.Event)
-		if score > bestScore || (score == bestScore && (best == nil || r.ID < best.ID)) {
+		if score > bestScore {
 			bestScore = score
-			best = r
+			globs = []model.Rule{r}
+			continue
+		}
+		if score == bestScore {
+			globs = append(globs, r)
 		}
 	}
-	if exact != nil {
+	if len(exact) > 0 {
 		return exact
 	}
-	return best
+	return globs
 }
 
 func globSpecificity(pattern string) int {