The 4xl modal forced a tall-narrow shape that made eight inspectable
sections scroll forever, and every "open another agent" needed a
close-then-reopen because the modal occluded the list with a dim
backdrop. Reshape the detail surface as a right-docked inspector
panel:

- Modal gains a `variant` prop. `drawer-right` docks to the right edge
  full-height, drops the dim backdrop, and uses pointer-events-none on
  the outer container so clicks pass through to the agents list. The
  modal contract (centred + dim + click-to-dismiss) is unchanged for
  every other call site.
- AgentsPage detail uses `variant="drawer-right" size="xl"` (576 px on
  sm+, full-screen sheet on mobile). Click a different agent card in
  the list while the drawer is open and the drawer's content updates
  in place — no close + reopen.
- aria-modal=false in drawer mode (the page IS interactive); Esc and
  the explicit close button stay as the dismissal paths because
  click-outside would race with the list-click-to-switch interaction.
- New slide-in-right keyframe + .animate-slide-in-right utility paired
  with the existing apple-ease timing curve so the drawer's entrance
  matches the rest of the dashboard's motion language.

…e panel

The drawer's whole point is that the underlying list stays interactive
— pointer-events-none on the container lets mouse clicks pass through.
But the focus trap was still active, so keyboard users hit Tab inside
the drawer and got bounced back to the first focusable element forever
with no way to reach the agents list short of Esc-then-restart.

Add a fourth `trap` parameter to useFocusTrap (default true so all
existing call sites — ConfirmDialog / ShortcutsHelp / CommandPalette /
Modal — keep their current behaviour) and pass false from Modal when
`variant === "drawer-right"`. Initial focus and focus-restoration on
close still happen; only the Tab-cycling interception is skipped.

Same drawer-right variant rolled out to the other two list+inspect
flows on the dashboard:

- ProvidersPage.ProviderDetailModal — read-only provider inspector
  (auth status, model count, latency, model list). Click another
  provider card while open → drawer's content updates in place.
- SkillsPage.SkillDetailModal — installed-skill inspector with evolve
  panes. Same in-place switching benefit.

Skipped on purpose:
- MarketplaceDetailModal stays modal — install flow is transactional,
  not browse-comparing.
- All Create / Edit / Add form modals (Plugins / Models / Memory /
  Scheduler / McpServers) stay modal — drawer's click-through would
  silently drop in-flight form state.
- HandsPage HandDetailPanel uses its own bespoke JSX rather than the
  shared <Modal>, so converting it to drawer needs a full panel
  rewrite — out of scope here.

Stacks on #3166. HandDetailPanel rolled its own backdrop + inner panel
JSX rather than using the shared <Modal>, so the drawer migration here
is a small refactor rather than a one-line variant flip:

- Replace the bespoke fixed-inset wrapper with <Modal isOpen onClose={...}
  variant="drawer-right" size="2xl" hideCloseButton>. The hero header
  keeps its own X close button (lines up with the existing visual).
- Hero header switches from shrink-0 to sticky top-0 bg-surface z-10 so
  identity + close stay reachable during scroll. Modal wraps children
  in a single overflow-y-auto, so any inner overflow-y-auto becomes a
  nested scroll inside a drawer — drop the body's flex-1 overflow-y-auto
  wrapper accordingly.
- TomlViewer (manifest viewer sub-modal) was previously rendered as a
  sibling of the inner panel inside the outer fixed-inset div. Lifts to
  a sibling of <Modal> inside a fragment so it renders as its own modal
  on top.

The 90% benefit applies here just like agents/providers/skills: with
the dim backdrop gone (drawer mode keeps the hands list interactive),
clicking another hand card while the drawer is open switches its
content in place. Focus trap is already disabled in drawer mode by
the Modal-level fix from the parent PR.