Adds native arm64 macOS support on top of #88's Intel macOS layer.
The one structural change arm64 needs is an address model. The port realises
the N64's 32-bit address space *as host addresses* — DRAM at 0x70000000, cart
at 0x10000000, plus ~1700 linker-absolute symbols — which is only sound while
host addresses fit in 32 bits. Native arm64 cannot map below 4 GiB
(__PAGEZERO; a shrunken pagezero is SIGKILLed at exec; PIE is mandatory;
MAP_32BIT fails). So the whole space is relocated to a fixed host base,
PORT_ADDR_BASE (16 TiB), with portN64ToHost / portHostToN64 / PORT_N64PTR as
the conversion chokepoints. PORT_ADDR_BASE is 0 on every other platform, so
all of this is an identity there.
That relocation then surfaces a class of latent 64-bit bugs that are invisible
at base 0 — any place the decomp round-trips a pointer through a 32-bit
integer. The src/ changes here are that class: pointer-width/layout only, no
behaviour change, N64 branch textually unchanged, each documented in
docs/dev/findings.md (D298/M2).
Also: Mach-O absolute-symbol generation at the same base, #pragma weak ->
symbol equates, __x86_64__ -> PLATFORM_64BIT, Darwin crash handler/ucontext,
shm_open DRAM, the AppKit main-thread guard, and the sidecar generation that
was the real boot blocker.
Verified: 21/21 solo levels boot, render and run crash-free.
Opt-in Input.PdMouseAim (F10 "PD mouse aim"): in aim mode the port only
accumulates the mouse position and the game's own crosshair integrator is
driven by it with PD's mouse damp (0.01), instead of GEPD's per-poll
overwrite fighting the weapon's ~0.8 per-tick damp (write*damp^k jitter).
Hook: #ifdef PORT block in sub_GAME_7F067FBC (aim-mode branch only),
identity when off; Rule-2 sign-off given by the maintainer.
Integrated locally from PR #96 with review fixes: finding renumbered
D337 -> D332; GE_PDMOUSEAIM lookup cached (GE_ENVSTR; it ran every poll
and aim tick); "live env" comments corrected. Windows build clean; bunker1
golden 3/3. Feel A/B owed.
Dan Turner