Standalone binary builds — bun build --compile for macOS/Linux

[yashdev9274]

Description

Add standalone binary builds using bun build --compile for macOS (arm64, x64) and Linux (arm64, x64), attached to GitHub releases.

Expected Deliverables

• Build script: 4 targets (macOS arm64/x64, Linux arm64/x64)
• CI workflow: matrix build on tag push, upload to GitHub release
• Binary naming: supercode-{os}-{arch}
• Install script update: detect OS/arch, download binary
• Release checklist update

Why

Standalone binaries eliminate Node.js dependency. Single curl command to install and run.

Considerations

• bun build --compile is experimental
• Binaries are 40-60MB (bundled runtime)
• Cross-compilation may require CI runners per platform
• Consider macOS code signing