Add macOS arm64 runtime support and release artifacts

[kkorenn]

What changed

This PR contains the macOS arm64 runtime fixes plus the CI/release packaging needed to ship separate macOS x64 and arm64 archives.

Runtime and bootstrap fixes

• Adds arm64 / osx-arm64 to the shared build properties and solution configurations.
• Adds macOS arm64 native bootstrap dependencies (libdobby.a, libplthook.a) and updates the macOS x64 libplthook.a.
• Adds native macOS dlsym interpose support in osxentry.cpp because plthook cannot reliably patch modern macOS chained fixups in UnityPlayer.dylib.
• Exposes MLRegisterDlsymHook, MLRealDlsym, and MLMacOSJitCopy from the native bootstrap and keeps those symbols through the AOT/native link.
• Updates ModuleSymbolRedirect so macOS uses the native dlsym interpose path, while still using the real un-interposed dlsym when resolving genuine runtime symbols.
• Adds MLMacOSJitCopy support for arm64 JIT writes using pthread_jit_write_protect_np plus instruction-cache invalidation.
• Vendors an arm64-safe macOS native detour platform inside MelonLoader so the arm64 build actually uses MLMacOSJitCopy instead of falling back to MonoMod legacy mprotect / MonoPosix writes.

macOS launch/path fixes

• Ships a macOS launch helper that opens Terminal tailing the MelonLoader log for visibility.
• Improves .app path detection on macOS so MelonLoader can resolve the game bundle correctly.
• Improves Mono framework detection by falling back to a single .app bundle in the game directory when the process path is not already the bundle path.

CI/release fixes

• Builds both osx-x64 and osx-arm64 in the macOS GitHub workflow matrix.
• Uploads debug/release artifacts for both architectures.
• Packages MelonLoader.macOS.arm64.zip alongside the existing MelonLoader.macOS.x64.zip in GitHub releases.
• Updates softprops/action-gh-release@v3 inputs to tag_name / name, enables overwrite_files, and grants the nested release upload workflow contents: write so an existing tag release can be updated.

Why

Apple Silicon native macOS installs need both the runtime/bootstrap changes and a release artifact. The existing x64-only macOS release path forced Rosetta and did not handle the arm64 detour/JIT/dlsym path correctly.

Validation

• dotnet restore -p:Platform="arm64" -p:ForceRID="osx-arm64"
• dotnet build --no-restore -c Release -p:Platform="arm64" -p:ForceRID="osx-arm64" -p:Version="0.7.3"
• dotnet restore -p:Platform="x64" -p:ForceRID="osx-x64"
• dotnet build --no-restore -c Release -p:Platform="x64" -p:ForceRID="osx-x64" -p:Version="0.7.3"
• Fork tag release workflow v0.7.3 | Release: https://github.com/kkorenn/MelonLoader/actions/runs/27083213838
• Downloaded MelonLoader.macOS.arm64.zip from kkorenn/MelonLoader@v0.7.3 and verified:
  • MelonLoader.Bootstrap.dylib is Mach-O arm64.
  • Native symbols include MLMacOSJitCopy, MLRegisterDlsymHook, and MLRealDlsym.
  • MelonLoader.dll for net35, net472, and net6 contains MacOSArm64NativeDetourPlatform and MLMacOSJitCopy.

Both architecture builds succeeded with existing project warnings. The fork release workflow completed successfully and updated the existing v0.7.3 release assets.