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/map_header_bridge.h

@@ -0,0 +1,16 @@
+#ifndef FACTORIO_MAP_HEADER_BRIDGE_H
+#define FACTORIO_MAP_HEADER_BRIDGE_H
+#include "version_bridge.h"
+
+/* Three serialized MapTick fields; their individual meanings are not recovered. */
+typedef struct {
+  FactorioMapVersion version;
+  uint64_t tick_fields[3];
+} FactorioMapHeader;
+
+/* Input starts at the constructor's stream position, NOT at the ZIP or map start.
+ * 0 success, 1 short stream, 2 invalid argument/address, 3 execution budget.
+ * Only success modifies out. This is not a complete save/world parser. */
+int factorio_map_header_parse(const uint8_t *payload, size_t length,
+                             FactorioMapVersion version, FactorioMapHeader *out);
+#endif