agentbridge: @agentbridge/cli npm package with bin wrapper

[espetro]

Context

The npm bin is a 200-byte JS wrapper that detects platform/arch and spawns the right Bun-compiled binary. Zero install scripts, zero postinstall, zero runtime deps.

Tasks

• Update packages/cli/package.json with bin field, os/cpu matrices, files whitelist
• Write bin/agentbridge.js wrapper (200 bytes)
• Wrapper downloads binary from GitHub Releases on first run if not bundled
• npx @agentbridge/cli --version works
• bunx agentbridge --version works

Source

• packages/cli/package.json (modify)
• packages/cli/bin/agentbridge.js (new)
• Plan: .agents/plans/2026-06-14-v0.2.0-distribution-pivot.md