fix(orbit): outbox lost-update recovery and session hardening (#1159)

* fix(orbit): harden the guest outbox — recover lost suggestions, avoid a duplicate outbox

Two outbox robustness issues on the poll-based, non-atomic playlist
transport:

- Lost-update: a track a guest appends to its outbox can be wiped by a
  concurrent host sweep-clear before the host recorded it, leaving the
  suggestion lost AND stuck on "waiting on host" forever (it only clears
  once it reaches the host's play queue). The playlist read-modify-write
  can't be made atomic, so recover: re-send a pending suggestion the host
  hasn't recorded (absent from state.queue) past a grace window — the host
  dedupes by (user, trackId), so it's idempotent — and give up + toast past
  a 45s window so the row stops hanging. New pendingResend planner module
  with unit tests; suggest + tick share ensureTrackInOutbox.

- Duplicate outbox: a transient getPlaylists failure at join was swallowed
  to [], so the existing-outbox check missed and a second outbox was
  created. Distinguish "lookup failed" from "genuinely absent" and retry
  once before falling back to create.

New i18n key for the give-up toast across all locales.

* fix(orbit): reject non-http(s) schemes in share invites

normalizeShareServerUrl only prepends http:// when the server string doesn't
already start with "http", so an invite carrying a scheme like httpx:// or
https-phish:// slips through unchanged. Reject anything whose parsed protocol
isn't http(s) at parse time, before the known-server match. Add round-trip
tests covering the accepted and rejected schemes.

* fix(orbit): read exit-modal role fresh to avoid a stale keydown closure

The exit modal's Enter/Escape handler binds once per open (deps [isOpen]) and
closed over the role prop, so a role change while the modal was up would act
on a stale value. Read role from the store inside the action instead, and drop
the now-unused reactive subscription.

* docs(changelog): consolidate Orbit fixes into one block, add 1159

src/utils/orbit.ts

@@ -73,6 +73,7 @@ export {
 export {
   approveOrbitSuggestion,
   declineOrbitSuggestion,
+  ensureTrackInOutbox,
   evaluateOrbitSuggestGate,
   joinOrbitSession,
   leaveOrbitSession,
@@ -81,5 +82,10 @@ export {
   suggestOrbitTrack,
   type OrbitSuggestGateReason,
 } from './orbit/guest';
+export {
+  forgetPendingSuggestion,
+  planPendingResends,
+  resetPendingResendState,
+} from './orbit/pendingResend';
 export { sweepGuestOutboxes } from './orbit/sweep';
 export { cleanupOrphanedOrbitPlaylists } from './orbit/cleanup';