feat: migrate logs API from REST to IPC streaming (#4277)

* feat: migrate logs API from REST to IPC streaming

- Replace REST API `/logs` calls with IPC streaming implementation
- Add new `src-tauri/src/ipc/logs.rs` with `LogsMonitor` for real-time log streaming
- Implement duplicate stream prevention with level tracking
- Add frontend-backend communication via Tauri commands for log management
- Remove WebSocket compatibility, maintain IPC-only mode
- Fix duplicate monitoring task startup when toggling log service
- Add proper task lifecycle management with JoinHandle cleanup

* refactor: remove dead code from logs.rs to fix clippy warnings

- Remove unused `timestamp` field from LogItem struct
- Remove unused `client` field from LogsMonitor struct
- Remove unused methods: `is_fresh`, `get_current_monitoring_level`, `get_current_logs`
- Simplify LogsMonitor initialization by removing client dependency
- All clippy warnings with -D warnings now resolved

* refactor: extract duplicate fmt_bytes function to utils module

- Create new utils/format.rs module with fmt_bytes function
- Remove duplicate fmt_bytes implementations from traffic.rs and memory.rs
- Update imports to use shared utils::format::fmt_bytes
- Add comprehensive unit tests for fmt_bytes function
- Ensure DRY principle compliance and code maintainability

src-tauri/src/cmd/clash.rs

@@ -1,7 +1,12 @@
 use super::CmdResult;
 use crate::{
-    config::*, core::*, feat, ipc::IpcManager, process::AsyncHandler,
-    state::proxy::ProxyRequestCache, wrap_err,
+    config::*,
+    core::*,
+    feat,
+    ipc::{self, IpcManager},
+    process::AsyncHandler,
+    state::proxy::ProxyRequestCache,
+    wrap_err,
 };
 use serde_yaml::Mapping;
 use std::time::Duration;
@@ -572,3 +577,23 @@ pub async fn is_clash_debug_enabled() -> CmdResult<bool> {
 pub async fn clash_gc() -> CmdResult {
     wrap_err!(IpcManager::global().gc().await)
 }
+
+/// 获取日志 (使用新的流式实现)
+#[tauri::command]
+pub async fn get_clash_logs(level: Option<String>) -> CmdResult<serde_json::Value> {
+    Ok(ipc::get_logs_json(level).await)
+}
+
+/// 启动日志监控
+#[tauri::command]
+pub async fn start_logs_monitoring(level: Option<String>) -> CmdResult {
+    ipc::start_logs_monitoring(level).await;
+    Ok(())
+}
+
+/// 清除日志
+#[tauri::command]
+pub async fn clear_logs() -> CmdResult {
+    ipc::clear_logs().await;
+    Ok(())
+}