fix: sanitize sidecar launch environment

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

tests/main/sidecarEnvironment.test.ts

@@ -0,0 +1,34 @@
+import { describe, expect, test } from 'bun:test';
+
+import { createSidecarEnvironment } from '@main/sidecar/sidecarEnvironment';
+
+describe('createSidecarEnvironment', () => {
+  test('removes inherited Copilot loader variables before spawning the sidecar', () => {
+    expect(
+      createSidecarEnvironment({
+        PATH: 'C:\\tools',
+        COPILOT_CLI: '1',
+        COPILOT_LOADER_PID: '1234',
+        copilot_run_app: '1',
+        NODE_OPTIONS: '--no-warnings',
+        electron_run_as_node: '1',
+      }),
+    ).toEqual({
+      PATH: 'C:\\tools',
+    });
+  });
+
+  test('preserves unrelated environment variables', () => {
+    expect(
+      createSidecarEnvironment({
+        PATH: 'C:\\tools',
+        HOME: 'C:\\Users\\mail',
+        FORCE_COLOR: '1',
+      }),
+    ).toEqual({
+      PATH: 'C:\\tools',
+      HOME: 'C:\\Users\\mail',
+      FORCE_COLOR: '1',
+    });
+  });
+});