Support multiple Honcho instances

[offendingcommit]

Problem

Today the app stores a single Honcho connection in localStorage under openconcho:config (baseUrl + optional token). Users running multiple Honcho deployments (local dev, staging, self-hosted prod, hosted) have to re-enter credentials every time they switch.

Proposal

• Store an array of named connections (e.g. { id, name, baseUrl, token }[]) plus an activeId.
• Add an instance switcher in the sidebar (or topbar) — quick swap without re-typing.
• Settings page: list/add/edit/delete instances; mark one as active.
• Persist last-used instance per app launch.
• Migrate existing single-config users transparently on first load.

Considerations

• Token storage is still localStorage — document the trust model.
• TanStack Query cache should be keyed/scoped so switching doesn't show stale data from another instance.
• Connection check (checkConnection()) should run per active instance.