fix: 修复关闭软件后 OpenCode 进程泄漏问题

- 使用 taskkill /F /T 强制终止进程树
- 在 before-quit 中 await 等待服务停止完成
- 修复 stop 方法中可能的空指针问题

electron/services/opencodeService.ts

@@ -1,4 +1,4 @@
-import { spawn, ChildProcess } from 'child_process';
+import { spawn, exec, ChildProcess } from 'child_process';
 import log from 'electron-log';
 
 const OPENCODE_PORT = 4096;
@@ -150,21 +150,33 @@ class OpenCodeService {
     try {
       log.info('[OpenCodeService] Stopping...');
 
-      this.process.kill('SIGTERM');
-      
-      await new Promise<void>((resolve) => {
-        setTimeout(resolve, 1000);
-      });
-
-      if (this.process && !this.process.killed) {
-        this.process.kill('SIGKILL');
-      }
-
+      const pid = this.process.pid;
       this.process = null;
       this._isRunning = false;
-      this.restartAttempts = 0;
 
-      log.info('[OpenCodeService] Stopped');
+      if (pid && process.platform === 'win32') {
+        return new Promise((resolve) => {
+          exec(`taskkill /F /T /PID ${pid}`, (error) => {
+            if (error) {
+              log.warn('[OpenCodeService] taskkill failed, process may already be dead:', error.message);
+            }
+            this.restartAttempts = 0;
+            log.info('[OpenCodeService] Stopped');
+            resolve({ success: true });
+          });
+        });
+      } else if (pid) {
+        this.process?.kill('SIGTERM');
+        await new Promise<void>((resolve) => setTimeout(resolve, 1000));
+        if (this.process && !this.process.killed) {
+          this.process.kill('SIGKILL');
+        }
+        this.restartAttempts = 0;
+        log.info('[OpenCodeService] Stopped');
+        return { success: true };
+      }
+
+      this.restartAttempts = 0;
       return { success: true };
     } catch (error: any) {
       log.error('[OpenCodeService] Failed to stop:', error);