Fix documentation to address Xcode behavior where 'Simulate Background
Fetch' menu item only appears when app is NOT running.
Changes:
- Add explicit note about Xcode menu item availability
- Prioritize LLDB command method when app is running (recommended)
- Document three methods: LLDB command, Xcode menu, and UI button
- Add troubleshooting section for common issues
- Update quick start section to reference LLDB method
- Explicitly reference test-apps/ios-test-app path for clarity
This resolves confusion when 'Simulate Background Fetch' disappears
from Debug menu while app is running. LLDB command method works reliably
in all scenarios.
b3d0d97834