Step 7 of the Vue→React migration. Ports the overview/index entry: dashboard
page, status + xray cards, panel-update / log / backup / system-history /
xray-metrics / xray-log / version modals, and the custom-geo subsection. Adds
the shared JsonEditor (CodeMirror 6) and useStatus hook used by the config
modal. Removes the unused react-hooks/set-state-in-effect disables now that
the rule is off globally.
