Per mara's review on this PR: the labelled SelectField-based picker
read as way too heavy for a passive-until-touched setting - a full
label+bordered-control form field row above the table. Replace it with
a compact inline "clock icon - value - chevron" control (a native
<select> still drives the interaction, just stripped of SelectField/
FormField's chrome), quiet until hovered/focused the same way
LinksMenu's header button is.
Also move it out of the panel body entirely: Panel gains an `actions`
slot in its title row (right-aligned via margin-left: auto), so the
picker sits next to the "hives" heading instead of taking its own row
and pushing the table down - per the design guide's own "a control
belongs next to the thing it affects" rule.
Verified with headless chromium screenshots (full page + a tight
close-up crop) against the built bundle: the picker now reads as
"(clock) 30s (chevron)" inline with the panel title, no extra vertical
space taken from the table. Added a Panel "with actions" demo to
ComponentsPage.
Closes#3446.
New ui/refresh-interval/RefreshInterval — a RefreshIntervalPicker
(off/10s/30s/1m preset select) plus a useRefreshInterval hook that
polls on that cadence, pausing while the document is hidden and
resyncing immediately on becoming visible again (same pattern
RelativeTime already uses). The hook keeps the caller's onTick fresh
via a ref rather than an effect dependency, so a new closure each
render doesn't re-arm the timer.
HivesPage wires it in: defaults to 30s (no inputs on this page to
interrupt, and the point of the feature is not needing a manual
reload), replacing the old fetch-once-at-mount effect. A successful
refresh also clears any previous fetch error instead of leaving a
stale failure on screen after the data's recovered.
Verified: tsc clean, build succeeds, screenshotted the hives page
(auto-loads on mount, picker defaults to 30s) and the components page
demo.
