feature: add apple silicon native macOS support (#81)

* feature: add apple silicon native macOS support - #81

* (macos): Fix crash

This fixes a crash when viewing the rear camera

* fix(macos): keep interpolated presentation on main thread

* fix(macos): supply Retro-WFC payload during setup

* perf(windows): compile out flat-memory fallback check

* remove duplicate smoke test

* test(macos): name and focus host platform tests

* fix(macos): validate Retro-WFC payload cache

* fix(payload): preserve staged file access failures

* Limit flat-page checks to variable-page hosts

---------

Co-authored-by: patchzyy <64382339+patchzyy@users.noreply.github.com>

runtime/include/fiber_manager.h

@@ -6,6 +6,7 @@
 #include <mutex>
 #include <thread>
 #include <unordered_map>
+#include <vector>
 
 #if defined(_WIN32)
 #ifndef NOMINMAX
@@ -22,7 +23,7 @@
 // Forward declarations
 struct CpuContext;
 
-// GuestFiberManager: each guest OSThread maps to a Windows Fiber. A scheduler fiber picks
+// GuestFiberManager: each guest OSThread maps to a host context. A scheduler context picks
 // which guest fiber runs; a real timer thread queues VI retraces at the VI cadence. Guest
 // threads only switch at explicit yield points (OSSleepThread, OSYieldThread, ...), matching
 // Wii cooperative semantics exactly.
@@ -39,7 +40,7 @@ enum class ThreadState : uint32_t {
 
 // Information about a guest fiber
 struct GuestFiber {
-    void* fiber = nullptr;              // Windows fiber handle
+    void* fiber = nullptr;              // Host context handle
     uint32_t entryPoint = 0;            // Thread entry function
     uint32_t entryArg = 0;              // Argument to entry function
     CpuContext cpuContext{};            // Saved CPU context for this fiber
@@ -102,10 +103,6 @@ private:
     static void CALLBACK FiberProc(void* param);
 #else
     static void FiberProc(void* param);
-    // libco's co_create() entry points take no argument (unlike CreateFiber's FiberProc(void*)),
-    // so this trampoline reads the guest thread address staged by CreateGuestFiber() and forwards
-    // into the (platform-neutral-bodied) FiberProc above. See fiber_manager.cpp.
-    static void FiberProcTrampoline();
 #endif
     // Switch from whichever fiber is currently active straight to the scheduler fiber, without
     // the SwitchToThread bookkeeping (CPU context save/restore, s_currentGuestThread). Used for
@@ -117,9 +114,8 @@ private:
     static std::mutex s_mutex;
     static std::unordered_map<uint32_t, GuestFiber> s_fibers;
     static std::vector<void*> s_fibersPendingDelete;
-    // The scheduler's own "fiber": a Windows HFIBER, or (non-Windows) libco's cothread_t for
-    // whichever native call stack first called GuestFiberManager::Initialize() - both are
-    // plain void* handles, so one field serves both platforms.
+    // The scheduler's own host context. Its opaque handle is supplied by the
+    // active HostContext backend, so one field serves every supported host.
     static void* s_schedulerFiber;
     static uint32_t s_currentGuestThread;
     static bool s_initialized;
@@ -135,4 +131,3 @@ private:
 extern std::atomic<uint32_t> g_viRetracePendingCount;
 
 } // namespace Fiber
-