docs(readme): rewrite around container runtime positioning

[PeronGH]

Summary

• Rewrite README around container runtime positioning, with plainer prose
• Reorganize: quick start moved above containers, platform section led with bring-your-own-machine
• Add AI agent and ArcBox Platform vision section; trim and de-dupe

Test plan

• Read through rendered README on GitHub for formatting/flow

[Copilot]

Pull request overview

This PR rewrites the top-level README to reposition ArcBox primarily as a fast, open-source Docker/OrbStack alternative for macOS, with additional sections covering Kubernetes, sandboxes (microVMs), and longer-term “ArcBox Platform” direction.

Changes:

• Reworked “Why ArcBox” messaging and project positioning around macOS container runtime + open-source framing.
• Reorganized the flow (Quick start moved up; expanded Containers/Kubernetes/Sandboxes/Machines sections).
• Updated badges/links and added/trimmed sections (built-from-scratch details, roadmap, and updated requirements/contributing text).

[pullfrog]

✅ No new issues found.

Reviewed changes — a docs-only rewrite of README.md that repositions ArcBox as a fast, open-source container runtime for macOS (Docker Desktop / OrbStack alternative) rather than an AI-agent sandbox engine. I verified every factual and command claim against the codebase.

• CLI rename arcbox → abctl — matches the real binary; app/arcbox-cli/Cargo.toml declares [[bin]] name = "abctl" and the arcbox bin is now a placeholder.
• Reorder + new sections — quick start moved above containers; adds Sandboxes, Bring your own machine (ArcBox Platform), Built from scratch, and an OrbStack comparison table.
• All example commands exist — daemon start, docker enable/setup, doctor, k8s start/kubeconfig, migrate from docker-desktop/orbstack, sandbox create/run/checkpoint/restore, machine create/start/list all map to real subcommands.
• Badge/link updates — LICENSE-MIT badge target exists, rust-1.96+ matches the workspace rust-version, and the get.arcbox.dev install URL matches scripts/install.sh.

A few accuracy points worth calling out, all of which check out:

• The "Shell and SSH access into a running machine is coming" claim is correct — the machine exec RPC currently returns Status::unimplemented in app/arcbox-api/src/grpc/machine.rs, so the abctl machine ssh/exec CLI commands don't function yet.
• The amd64/FEX claim ("x86-64 is translated inside the guest by FEX, with nothing to configure") is backed by RuntimeTranslator::Fex in app/arcbox-docker/src/routing.rs and the bundled FEX64 runtime in the boot assets.

Nothing blocking.

  ^{｜ Fix it ➔ ｜ View workflow run ｜ Using Claude Opus ｜ 𝕏}

[greptile-apps]

Greptile Summary

This PR rewrites the README around ArcBox's container-runtime positioning. The main changes are:

• New quick-start-first structure.
• Expanded containers, Kubernetes, sandbox, machine, and platform sections.
• Updated requirements, badges, and product positioning.
• Trimmed older limitations and duplicated runtime prose.

Confidence Score: 4/5

The README should be corrected before merging because it documents unsupported user workflows as ready today.

• docker build is now shown as a working container flow even though the prior README marked it unsupported.
• linux/amd64 image support is now presented as ready without matching runtime changes in this PR.
• The sandbox checkpoint example may pass a snapshot name where the restore command expects an ID.

README.md

Important Files Changed

Filename	Overview
README.md	Large documentation rewrite with several capability claims promoted to working examples.

_{Reviews (1): Last reviewed commit: "docs(readme): trim Why ArcBox and de-dup..." | Re-trigger Greptile}