feat: implement CmdProxyState for managing proxy refresh state and add state management module

refactor: remove unnecessary macOS conditional compilation directive

src-tauri/src/state/mod.rs

@@ -0,0 +1,4 @@
+// Tauri Manager 会进行 Arc 管理，无需额外 Arc
+// https://tauri.app/develop/state-management/#do-you-need-arc
+
+pub mod proxy;

src-tauri/src/state/proxy.rs

@@ -0,0 +1,15 @@
+pub struct CmdProxyState {
+    pub last_refresh_time: std::time::Instant,
+    pub need_refresh: bool,
+    pub providers_proxies: serde_json::Value,
+}
+
+impl Default for CmdProxyState {
+    fn default() -> Self {
+        Self {
+            last_refresh_time: std::time::Instant::now(),
+            need_refresh: true,
+            providers_proxies: serde_json::Value::Null,
+        }
+    }
+}