feat: 拆分评审与提交消息提示词并增加 hook 备份与 JSON 输出

- 新增 custom_reviewer_prompt 和 custom_commit_msg_prompt，兼容旧 custom_prompt
- pre-commit hook 安装时备份已有 hook，卸载时恢复
- 支持 --format json 输出评审结果
- diff 发送前自动脱敏敏感信息

internal/security/redact_test.go

@@ -0,0 +1,38 @@
+package security
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestRedactSecrets(t *testing.T) {
+	input := `
+  api_key = "sk-12345678901234567890"
+  Authorization: Bearer my-secret-bearer-token-123
+  password: "this-is-a-secret-password"
+  -----BEGIN RSA PRIVATE KEY-----
+  secret private key content
+	  -----END RSA PRIVATE KEY-----
+	  `
+	if strings.Contains(input, "[REDACTED_") {
+		t.Fatal("测试输入不应预先包含脱敏占位符")
+	}
+
+	output := RedactSecrets(input)
+	if output == input {
+		t.Fatal("RedactSecrets 未改变包含敏感信息的输入")
+	}
+	for _, secret := range []string{
+		"sk-12345678901234567890",
+		"my-secret-bearer-token-123",
+		"this-is-a-secret-password",
+		"secret private key content",
+	} {
+		if strings.Contains(output, secret) {
+			t.Fatalf("敏感信息未被脱敏: %q\noutput: %s", secret, output)
+		}
+	}
+	if !strings.Contains(output, "[REDACTED_SECRET]") || !strings.Contains(output, "[REDACTED_BEARER_TOKEN]") {
+		t.Fatalf("脱敏占位符不完整: %s", output)
+	}
+}