bug(desktop): macOS x64 build shows prohibited icon and cannot run on Intel Mac

Description

The current OpenCode Desktop V2 macOS x64 build is not usable on an Intel Mac. After mounting the official opencode-desktop-mac-x64.dmg, the OpenCode application icon shows the macOS prohibited symbol. Copying it to /Applications does not help, and the application cannot be launched.

The x64 artifact is available, but it appears to be incompatible with at least some Intel Mac hardware or macOS versions.

Steps to reproduce

1. Download the official opencode-desktop-mac-x64.dmg.
2. Mount the DMG on an Intel Mac.
3. Observe that the OpenCode icon has the prohibited symbol.
4. Drag OpenCode to Applications and try to launch it.

Actual behavior

macOS indicates that the application is incompatible, and OpenCode cannot be launched.

Expected behavior

The official x64 build should launch on supported Intel Macs. If only specific Intel CPUs or macOS versions are supported, please document the minimum CPU instruction set and macOS version clearly on the download page.

Additional context

This affects the Desktop V2 application. The failure occurs before the application can start, so no in-app logs are available.

Start by reproducing the failure with the official opencode-desktop-mac-x64.dmg on an Intel Mac and checking the artifact's supported CPU instructions and macOS version. Trace the Desktop V2 packaging and build configuration to identify the incompatibility; done means the x64 build launches on supported Intel Macs or the download page clearly documents its limits.