feat(scopes): add clients to scopes

[Litarnus]

This PR adds Client to scopes. With the future 2 scopes model, the Hub will no longer exist and clients will only exist on scopes.
When obtaining a Client, it will first check the isolation scope and if no client exists there, it will fall back to the global scope client

[cursor]

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[cursor]

Cursor Bugbot has reviewed your changes and found 3 potential issues.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit c86807c. Configure here.}