Simulator tweak injection and helpers

Drag an iOS app or tweak .deb file into a Simulator to install it

1. Download/build an iOS app or iOS tweak (.deb).
2. Boot a Simulator with simulator-trainer.
3. Drop the file onto the sim window and wait for a respring.

• Turns Simulator.app into a dylib and dlopens it for in-process swizzling.
• Mounts a writable tmpfs overlay on the simulator runtime.
  (one simruntime per iOS version, shared by every device model).
• Injects a loader into libobjc.A.dylib to start tweaks.
• Installs tweaks inside the overlay; non-sim binaries are auto-converted during install.