Unrelated to #2108's diagnostics work, folded in at the maintainer's request
rather than tracked separately.
The sticky full-bleed bar cost the whole view a band of vertical space for what
is a notification about one server, and it pushed down the monitoring sidebar
that an OAuth failure now opens. Every corner is spoken for — the toast stack
owns bottom-right, the right edge is the sidebar whose toolbar an anchored card
covers, top-left is the Servers header — so it is centered instead, which is
the one placement that reads as addressed to the window rather than attached to
the wrong panel.
Deliberately WITHOUT an overlay. This is a notification, not a decision that
must be made now, and blocking the page would force a choice between reading
the requests that explain the failure and keeping the affordance — dismissing
is not free, since "Authorize again" also clears the stale OAuth state, which a
plain reconnect does not do.
Kept as the existing declarative component rather than routed through Mantine's
`notifications`: that module is mocked in App.test.tsx, so switching would have
broken the ten tests asserting on this banner's text and its action button,
including the lost-authorization-state coverage. The message now stacks above a
right-aligned action, which a ~420px card needs.
Signed-off-by: cliffhall <cliff@futurescale.com>