refactor(core): 拆分 model/mqtt/update 为单一职责子模块

- model/ 按领域拆为 connection/subscription/message/publish/variable/log/settings
- mqtt/ 拆为门面(引擎与事件)、tls、v5、v4 四块
- update/ 拆为门面(版本工具与命名约定)、check(检查)、install(下载/安装/清理)
- sysmon 只保留进程资源采样，窗口置顶迁至新 platform.rs
- 对外路径经 mod.rs 再导出保持不变，测试随门面保留（33 通过）

gpui-app/src/model/log.rs

@@ -0,0 +1,45 @@
+//! 运行日志：日志级别与日志条目。
+
+
+
+
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum LogLevel {
+    Debug,
+    Info,
+    Warn,
+    Error,
+}
+
+impl LogLevel {
+    pub fn label(self) -> &'static str {
+        match self {
+            Self::Debug => "DEBUG",
+            Self::Info => "INFO",
+            Self::Warn => "WARN",
+            Self::Error => "ERROR",
+        }
+    }
+
+    pub fn parse(s: &str) -> Self {
+        match s {
+            "debug" => Self::Debug,
+            "warn" => Self::Warn,
+            "error" => Self::Error,
+            _ => Self::Info,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct LogEntry {
+    pub timestamp: i64,
+    pub connection_id: String,
+    pub level: LogLevel,
+    pub event: String,
+    pub message: String,
+    pub details: Option<String>,
+}
+
+// ─── 连接状态 ────────────────────────────────────────────────────────────────