SIGILL crash on AMD Ryzen Zen 3 (no AVX-512 support) — all sessions crash

Description

Version: 1.18.5
Platform: Linux x64
CPU: AMD Ryzen 5 5600H (Zen 3)
Installed from: /opt/OpenCode/ai.opencode.desktop (packaged binary)

Issue

OpenCode Desktop crashes with SIGILL (Illegal Instruction) on every session.
The binary contains AVX-512 instructions that AMD Zen 3 CPUs do not support.

Evidence

The compiled binary at /opt/OpenCode/ai.opencode.desktop includes AVX-512
instructions using zmm registers:

vaddps -0x1e2b8d2(%rip),%zmm0,%zmm8 ; EVEX-encoded, requires AVX-512
vfmadd213ps %zmm0,%zmm2,%zmm7 ; EVEX-encoded, requires AVX-512
kmovd %edi,%k0 ; AVX-512 mask register

Ryzen 5 5600H (Zen 3) flags include AVX and AVX2 but NOT AVX-512.

Coredump confirms all crashes are SIGILL on the main binary:

• 5+ cores, all signal=SIGILL, executable=/opt/OpenCode/ai.opencode.desktop

20+ crash dumps accumulated in Crashpad/pending/

Expected

Binary should be compiled without AVX-512, or with runtime dispatch
to fall back on CPUs lacking AVX-512 support.

Workaround

CLI (opencode command) works fine — uses system Node.js runtime
without the AVX-512 requirement.

Plugins

No response

OpenCode version

No response

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

No response

Terminal

No response