feat(通知模板): 支持缺字段按空值渲染与空行省略

Motivation:
统一 crypto-strategy 与 trade-signal 两类交易信号的模板字段，使同一套通知模板可复用；字段缺失或为空时不再导致渲染报错或输出空行，通知内容更整洁。

Changes:

* 渲染器缺失字段改为按空值处理，新增 line 函数实现空值整行省略
* crypto-strategy 信号补充止盈价、止损价、平均价、收益额等模板字段
* trade-signal 信号保留原始报文中的额外字段以适配统一模板
* 修复结构化日志将 error 作为值直接输出导致的格式问题

internal/engine/renderer.go

@@ -3,6 +3,7 @@ package engine
 import (
 	"bytes"
 	"fmt"
+	"strings"
 	"text/template"
 )
 
@@ -13,7 +14,10 @@ func NewRenderer() *Renderer {
 }
 
 func (r *Renderer) Render(tmplContent string, data map[string]interface{}) (string, error) {
-	tmpl, err := template.New("notify").Option("missingkey=error").Parse(tmplContent)
+	tmpl, err := template.New("notify").
+		Option("missingkey=zero").
+		Funcs(template.FuncMap{"line": templateLine}).
+		Parse(tmplContent)
 	if err != nil {
 		return "", fmt.Errorf("parse template: %w", err)
 	}
@@ -23,3 +27,34 @@ func (r *Renderer) Render(tmplContent string, data map[string]interface{}) (stri
 	}
 	return buf.String(), nil
 }
+
+// templateLine renders "label：value\n" or empty if value is missing/zero.
+func templateLine(label string, v any) string {
+	if isEmptyValue(v) {
+		return ""
+	}
+	return label + "：" + fmt.Sprint(v) + "\n"
+}
+
+func isEmptyValue(v any) bool {
+	switch t := v.(type) {
+	case nil:
+		return true
+	case string:
+		return strings.TrimSpace(t) == ""
+	case bool:
+		return !t
+	case int:
+		return t == 0
+	case int32:
+		return t == 0
+	case int64:
+		return t == 0
+	case float32:
+		return t == 0
+	case float64:
+		return t == 0
+	default:
+		return false
+	}
+}

internal/engine/renderer_test.go

@@ -18,10 +18,41 @@ func TestRenderer(t *testing.T) {
 	}
 }
 
-func TestRenderer_Error(t *testing.T) {
+func TestRendererMissingKeyEmpty(t *testing.T) {
 	r := NewRenderer()
-	_, err := r.Render("{{.nonexistent}}", map[string]interface{}{})
-	if err == nil {
-		t.Error("expected error for missing field, got nil")
+	_, err := r.Render("x{{.nonexistent}}y", map[string]interface{}{})
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestRendererLineOmitsEmpty(t *testing.T) {
+	r := NewRenderer()
+	tmpl := `{{line "币种" .symbol}}{{line "平均价" .totalAvgPx}}{{line "价格" .price}}{{line "止损价" .stopLossPrice}}`
+	out, err := r.Render(tmpl, map[string]interface{}{
+		"symbol":        "ICP",
+		"price":         2.273,
+		"totalAvgPx":    "",
+		"stopLossPrice": 0,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(out, "币种：ICP") || !strings.Contains(out, "价格：2.273") {
+		t.Fatalf("out=%q", out)
+	}
+	if strings.Contains(out, "平均价") || strings.Contains(out, "止损价") {
+		t.Fatalf("empty lines should be omitted, out=%q", out)
+	}
+}
+
+func TestRendererLineMissingKey(t *testing.T) {
+	r := NewRenderer()
+	out, err := r.Render(`{{line "平均价" .totalAvgPx}}{{line "币种" .symbol}}`, map[string]interface{}{"symbol": "ICP"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(out, "平均价") || !strings.Contains(out, "币种：ICP") {
+		t.Fatalf("out=%q", out)
 	}
 }