Show sandbox nodes around Core and simplify node enrollment

[SaladDay]

The Hosted Sandbox Manager now puts nodes around Core in a desktop topology, with connection-state animation, node selection and details, and secondary deployment metadata. Add node opens a compact verified installation command with clipboard feedback and enrollment progress. Chinese/English, keyboard access, reduced motion, existing authorization and resource guards are preserved; mobile redesign is deferred.

Initial setup uses a usable HTTPS console origin automatically and requires an explicit reachable address for loopback or unspecified origins. The installer reports its progress without printing credentials. No scheduling or provider lifecycle behavior changes.

Validation:

• Typecheck, Web/client unit tests, Node 22 production build, command shell behavior tests and 13 installer tests passed.
• 123 browser cases passed, excluding four Dashboard cases that also fail on the untouched comparison base (437858d).
• make check was run: backend/database/generated/distribution/SDK checks passed; it stops at those four pre-existing Dashboard failures. Remaining Mcode and Rust executor gates passed separately. This is not a fully green make check result.
• Independent blind review findings were fixed and verified. Real mx1 desktop checks covered both nodes, light/dark Chinese UI, details, command clipboard, reduced motion and language switching.
• The generated command installed a temporary node on mx2 and initialized a real microsandbox Runtime in a no-input Session. No model call was made; owned test resources were removed. Private-CA trust is a documented host prerequisite.