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_test.go

@@ -60,3 +60,32 @@ func TestPickEventRuleNoMatch(t *testing.T) {
 		t.Fatal("expected no match")
 	}
 }
+
+func TestPickEventRulesAllExactMatches(t *testing.T) {
+	rules := []model.Rule{
+		{ID: 12, Event: "trade.*", Enabled: 1},
+		{ID: 17, Event: "trade.close", Enabled: 1},
+		{ID: 18, Event: "trade.close", Enabled: 1},
+		{ID: 19, Event: "trade.close", Enabled: 0},
+	}
+	got := PickEventRules("trade.close", rules)
+	if len(got) != 2 {
+		t.Fatalf("want 2 exact trade.close, got %#v", got)
+	}
+	ids := []int{got[0].ID, got[1].ID}
+	if ids[0] != 17 || ids[1] != 18 {
+		t.Fatalf("ids=%v", ids)
+	}
+}
+
+func TestPickEventRulesSameGlobBoth(t *testing.T) {
+	rules := []model.Rule{
+		{ID: 1, Event: "trade.*", Enabled: 1},
+		{ID: 2, Event: "trade.*", Enabled: 1},
+		{ID: 3, Event: "*", Enabled: 1},
+	}
+	got := PickEventRules("trade.open", rules)
+	if len(got) != 2 {
+		t.Fatalf("want both trade.*, got %#v", got)
+	}
+}