[NathanFlurry]

• Replace the local agentOS setup flow (agent, software, and sandbox pickers plus generated `rivetkit/agent-os` server code, which no longer works) with a connect step for the managed agentOS service.
• Show TypeScript (`@rivet-dev/agentos`) and curl examples with the namespace and token filled in, a tab-aware copy prompt, and a docs link. When the namespace has no token, as in OSS without auth, the examples and copy leave the token out.
• Treat agentOS as a managed service: skip the platform deploy step and provision the services pool when it is selected. Still gated by the `agent-os` feature flag.
• Show the product picker as a single list without Products and Services headings.
• Remove the unused setup builder, selection steps, catalog, and story; add tests and stories for the connect guide.

[NathanFlurry]

Stack for rivet-dev/rivet

• #5900 chore: remove leftover agent-os references
• #5899 feat(frontend): onboard agentOS through the managed service 👈
• #5898 chore: fix rustfmt and biome formatting
• main

Get stack: forklift get 5899
Push local edits: forklift submit
Merge when ready: forklift merge 5899

_{change qqnupqov}

[NathanFlurry]

Dropping the onboarding change; not needed.