Agents: Enhance account menu UI and chat status tooltip (#313001)

* feat: add color theme selection to account menu and adjust UI padding

* style: enhance chat status tooltip appearance and layout

Co-authored-by: Copilot <copilot@github.com>

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Co-authored-by: mrleemurray <mrleemurray@users.noreply.github.com>
Co-authored-by: Copilot <copilot@github.com>