Package and launch Atrium

[eamirian]

Outcome

Atrium becomes an installed ACE application rather than a source-checkout demo. ace atrium serves the production bundle on loopback and forwards governed API calls same-origin to the configured Core runtime.

Included

• packaged production Atrium assets in the Core wheel and sdist
• ace atrium loopback launcher with optional browser open
• same-origin Core API forwarding with fail-closed route collision handling
• reuse of the already-issued CLI bearer token without embedding API keys
• installed-asset, host, proxy, and CLI tests

Verification

• rebased onto Core main through personal ownership and Ask ACE
• focused Atrium, Builder host, API, and CLI: 43 passed
• current Canvas production package build passed
• wheel and sdist build passed
• clean isolated wheel install passed with all 157 dependencies
• installed ace atrium --help and current hashed static assets verified from /private/tmp, outside the checkout
• Ruff and diff checks passed

Boundary

ace atrium is checkout-free, but it expects an already-running configured Core API. Checkout-free setup/runtime is provided separately on main; the live installed service-start acceptance and single-user authority bootstrap remain v1 gates. This PR does not add domain logic or widen authority.