fix: resolve macos bun interop

Use Bun-safe Electron and child_process import patterns for macOS GitHub Actions tests.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/sidecar/sidecarProcess.ts

@@ -1,4 +1,4 @@
-import { app } from 'electron';
+import electron from 'electron';
 import { spawn, type ChildProcessWithoutNullStreams } from 'node:child_process';
 
 import type {
@@ -23,6 +23,8 @@ import {
 import { TurnCancelledError } from '@main/sidecar/turnCancelledError';
 import { resolveSidecarProcess } from '@main/sidecar/sidecarRuntime';
 
+const { app } = electron;
+
 type PendingCommand =
   | ({
       processId: number;