Build and Run GridRacer

Quick iteration: build the app and launch in simulator.

Steps

1. Detect simulator:

   SIMULATOR=$(xcrun simctl list devices available | grep -E "iPhone (16|15|14)" | grep -v unavailable | head -1 | sed -E 's/.*iPhone ([0-9]+).*/iPhone \1/')
   echo "Using: $SIMULATOR"
   

2. Build (stop on failure):

   xcodebuild -scheme GridRacer -configuration Debug -destination 'generic/platform=iOS Simulator' build 2>&1 | grep -E "(error:|warning:|BUILD|FAILED|SUCCEEDED)" | tail -20