feat: support arm64 Linux simulator-server binary

[filip131311]

Summary

The only Linux simulator-server binary argent ships today is x86_64 (simulator-server-argent-linux — verified: ELF 64-bit … x86-64). On arm64 Linux hosts (Lima/UTM VMs on Apple Silicon, arm cloud instances, Raspberry Pi-class devices) the package has no usable binary — the x86_64 ELF would only fail with ENOEXEC at spawn time.

This PR teaches the whole binary pipeline about a host platform key: process.platform everywhere, except arm64 Linux which maps to linux-arm64. macOS keeps a single darwin/ dir because its binary is universal (lipo); Linux binaries are single-arch ELFs, so each arch gets its own platform-keyed directory. x86_64 Linux keeps the existing linux key for backward compatibility.

Changes

• @argent/native-devtools-ios resolver — new exported hostPlatformKey(); simulatorServerBinaryPath() resolves bin/linux-arm64/ on arm64 Linux and names the searched key in its error message.
• argent-simulator-server.cjs dispatcher (npm bin entry) — mirrors the same key (duplicated deliberately; the dispatcher ships as a standalone file).
• bundle-tools.cjs — linux-arm64 added to the supported host platform dirs; copied into the package when staged, warn-and-skip otherwise (same as x86_64 Linux).
• scripts/download-simulator-server.sh — downloads simulator-server-argent-linux-arm64 into bin/linux-arm64/; tolerates the asset being absent (warn + skip) until the upstream release ships it, so publishing keeps working in the meantime.
• scripts/dev.cjs — copies the current host's binary by key.
• publish / publish-next / build-package-artifact workflows — linux-arm64 added to the binary inventory; gated by the existing ARGENT_REQUIRE_LINUX_BINARY flag (now covering both Linux keys via a linux* glob).

Tests

• Resolver: new arch-aware suite — linux+arm64 → bin/linux-arm64, linux+x64 → bin/linux, darwin+arm64 → bin/darwin, and the missing-binary error names linux-arm64.
• Dispatcher: end-to-end test faking process.platform/process.arch in a child process to exercise the real resolution path on any host.
• Full suite: 146 files / 1651 tests pass. tsc --build clean.
• download-simulator-server.sh exercised against the live radon-main release: downloads darwin + linux, warn-and-skips the not-yet-published arm64 asset.

Dependencies

Companion PR software-mansion/radon#126 adds the ubuntu-24.04-arm build leg that publishes simulator-server-argent-linux-arm64 to simulator-server-releases. This PR is safe to merge first (the download script and verify steps tolerate the missing asset); arm64 hosts start working once a release containing the new asset is cut.

[filip131311]

End-to-end validation against real binaries — the companion workflow (software-mansion/radon#126) was dispatched from its branch and published a complete test release including simulator-server-argent-linux-arm64. Ran scripts/download-simulator-server.sh against that tag:

Downloading simulator-server-argent-macos → bin/darwin/simulator-server
  ✓ arch ok: Mach-O universal binary with 2 architectures: [x86_64…] [arm64]
Downloading simulator-server-argent-linux → bin/linux/simulator-server
  ✓ arch ok: ELF 64-bit LSB pie executable, x86-64, …
Downloading simulator-server-argent-linux-arm64 → bin/linux-arm64/simulator-server
  ✓ arch ok: ELF 64-bit LSB pie executable, ARM aarch64, …

The downloaded arm64 binary was also executed on an aarch64 Linux VM (Lima): --help and fingerprint both succeed.

The ✓ arch ok lines come from 150c0f2, which adds a file(1)-based architecture gate to the download script: a present-but-wrong-arch asset now fails the download hard (a wrong-arch binary is worse than a missing one — the resolver would pick it and the user would get a bare ENOEXEC). Missing assets keep the existing warn-and-skip behavior. The publish workflows' inventory also logs file output per binary.