feat(protocol): shareable public booking link bar in Room Bookings

Task #655: staff need a one-click way to copy and share the public
(no-login) room-booking link with guests.

- Add a link bar at the top of the "حجوزات القاعات" (Room Bookings)
  section showing the absolute public URL, with a "نسخ الرابط" copy
  button that gives toast + a temporary "تم النسخ" confirmation state.
- URL is built from window.location.origin + BASE_URL (trailing slash
  stripped) + "/protocol/request", so it works on root and subpath
  deploys and when pasted into a browser/WhatsApp.
- Clipboard uses navigator.clipboard with a textarea+execCommand
  fallback; fallback now checks execCommand's return and reports failure
  (destructive toast) instead of falsely showing success. Textarea is
  removed in a finally block. Copied-state timer stored in a ref and
  cleared on repeat clicks to avoid a reset race.
- URL text forced dir="ltr" inside the RTL layout; new i18n keys
  (shareLinkTitle, copyLink, linkCopied, linkCopyFailed) added under
  protocol.bookings in both ar.json and en.json.

Verified: tsc typecheck passes; /protocol serves 200; module transforms
cleanly via Vite; architect review issues (fallback false-success,
timer race) fixed.

artifacts/tx-os/src/locales/en.json

@@ -1594,7 +1594,11 @@
       "startsAt": "From",
       "endsAt": "To",
       "viewList": "List",
-      "viewCalendar": "Calendar"
+      "viewCalendar": "Calendar",
+      "shareLinkTitle": "Public booking link (share with guests)",
+      "copyLink": "Copy link",
+      "linkCopied": "Link copied",
+      "linkCopyFailed": "Could not copy the link"
     },
     "external": {
       "new": "New meeting",