- Only call autokill on main thread to avoid killing children during worker teardown
- Remove process group kill (-pid) that was killing Bun itself before shutdown
- Add Windows platform guards to skip Unix-specific autokill tests
Fixes:
1. VirtualMachine.onExit now checks isMainThread() before calling killAllChildProcesses
2. autokill.zig no longer uses kill(-pid) which killed Bun's own process
3. test/cli/autokill.test.ts now skips on Windows with describe.skipIf(isWindows)