refactor(notification): 重构 PushPlusPlus 通知提供商

- 删除 PushPlusPlus 类和相关组件
- 新增 PushPlus 类和组件
- 更新通知提供商列表和相关配置
- 修改国际化文案，将 PushPlusPlus 改为 PushPlus

server/notification-providers/pushplus.js

@@ -0,0 +1,50 @@
+const NotificationProvider = require("./notification-provider");
+const axios = require("axios");
+const { DOWN, UP } = require("../../src/util");
+
+class PushPlus extends NotificationProvider {
+    name = "PushPlus";
+
+    /**
+     * @inheritdoc
+     */
+
+    async send(notification, msg, monitorJSON = null, heartbeatJSON = null) {
+        const okMsg = "Sent Successfully.";
+        const url = `https://www.pushplus.plus/send`;
+        try {
+            await axios.post(url, {
+                "token": notification.pushPlusSendToken,
+                "title": this.checkStatus(heartbeatJSON, monitorJSON),
+                "content": msg,
+                "template": "html"
+            }, { headers: { "Content-Type": "application/json" } }
+        );
+            return okMsg;
+
+        } catch (error) {
+            this.throwGeneralAxiosError(error);
+            console.error("PushPlus Error:", error.response?.data || error.message);
+            throw new Error("Notification failed: " + error.message);
+        }
+    }
+
+    /**
+     * Get the formatted title for message
+     * @param {?object} heartbeatJSON Heartbeat details (For Up/Down only)
+     * @param {?object} monitorJSON Monitor details (For Up/Down only)
+     * @returns {string} Formatted title
+     */
+    checkStatus(heartbeatJSON, monitorJSON) {
+        let title = "UptimeKuma Message";
+        if (heartbeatJSON != null && heartbeatJSON["status"] === UP) {
+            title = "UptimeKuma Monitor Up " + monitorJSON["name"];
+        }
+        if (heartbeatJSON != null && heartbeatJSON["status"] === DOWN) {
+            title = "UptimeKuma Monitor Down " + monitorJSON["name"];
+        }
+        return title;
+    }
+}
+
+module.exports = PushPlus;