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.

runtime/target_bridge.h

@@ -0,0 +1,13 @@
+#ifndef FACTORIO_TARGET_BRIDGE_H
+#define FACTORIO_TARGET_BRIDGE_H
+#include <stdint.h>
+
+typedef struct {
+  unsigned allocations, pool_capacity, initialized_targets;
+  uint64_t heap_bytes;
+} FactorioTargetProbe;
+/* Executes the original initialization graph in an isolated 1 MiB guest.
+ * 0 verified; 5 heap exhausted; 6 unsupported service; other values are errors.
+ * Result commits only after complete object-graph validation. */
+int factorio_target_probe(FactorioTargetProbe *out);
+#endif