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.

platform/native/shim/frameworks.m

@@ -0,0 +1,23 @@
+// Objective-C symbols missing from iOS Foundation and Metal.
+#import <Foundation/Foundation.h>
+#import "fx.h"
+
+#ifdef FX_LIB_FOUNDATION
+@interface NSAppleEventManager : NSObject
+@end
+@implementation NSAppleEventManager
++ (instancetype)sharedAppleEventManager { static NSAppleEventManager *m; static dispatch_once_t o; dispatch_once(&o, ^{ m = [self new]; }); return m; }
+- (void)setEventHandler:(id)handler andSelector:(SEL)sel forEventClass:(uint32_t)c andEventID:(uint32_t)e { }
+- (void)removeEventHandlerForEventClass:(uint32_t)c andEventID:(uint32_t)e { }
+@end
+#endif
+
+#ifdef FX_LIB_METAL
+#import <Metal/Metal.h>
+FX_EXPORT NSArray *MTLCopyAllDevicesWithObserver(id *observer, void (^handler)(id, NSString *)) {
+    if (observer) *observer = nil;
+    id device = MTLCreateSystemDefaultDevice();
+    return device ? @[device] : @[];
+}
+FX_EXPORT void MTLRemoveDeviceObserver(id observer) { }
+#endif