Native iPhone port of Factorio 2.0.77

Run the original macOS ARM64 game code on iOS:
- tools/retarget.py: header-only Mach-O retargeting to an iOS dylib
- platform/native: UIKit host and macOS API shims (AppKit for SDL's
  Cocoa backend, CoreGraphics displays, CoreAudio device, Metal device
  properties, Wuffs PNG decoding, Steam and peripheral stubs)
- touch, overlay, iOS keyboard and hardware keyboard input
- tools/build_native.py: build, sign, install, data copy, launch
- docs: build guide, controls, architecture

Also includes the earlier static-translation research (ARM64 -> WASM ->
native) under docs/research, runtime/, tests/ and tools/.

No game files are included; the build reads them from a local install.

.gitignore

@@ -0,0 +1,15 @@
+# Generated output, including anything derived from the game binary or data.
+/build/
+# Fetched tool sources (see README: wabt, SDL reference, Wuffs are fetched at pinned versions).
+/third_party/
+# Local reverse-engineering evidence exported from the user's installed copy.
+/evidence/
+/rea-evidence.json
+# Generated by xcodegen from platform/ios/project.yml.
+/platform/ios/FactorioPort.xcodeproj/
+__pycache__/
+*.pyc
+.DS_Store
+*.ipa
+*.dSYM/
+*.mobileprovision