Task #743: sidebar «إدارة القاعات» — clearer labels + submenu distinction

- ar.json: protocol.tabs.bookings «حجز القاعات»→«الحجوزات», bookingSettings «إعدادات الحجوزات»→«الإعدادات»
- en.json: "Room Bookings"→"Bookings", "Booking Settings"→"Settings"
- Same keys also serve as page headings (accepted per task), so headings change too.
- protocol.tsx: submenu children of roomsGroup and gifts group now wrapped in a
  container with md:ms-4 md:border-s-2 md:border-slate-300 md:ps-1 (vertical
  guide line + indent, RTL-safe logical props); removed per-button md:ps-6.
  Mobile horizontal layout unchanged.
- tx-os tsc clean; architect review passed.

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

@@ -1670,8 +1670,8 @@
       "dashboard": "لوحة المعلومات",
       "roomsGroup": "إدارة القاعات",
       "roomsDashboard": "لوحة القاعات",
-      "bookingSettings": "إعدادات الحجوزات",
-      "bookings": "حجز القاعات",
+      "bookingSettings": "الإعدادات",
+      "bookings": "الحجوزات",
       "external": "اجتماعات خارجية",
       "giftsGroup": "الهدايا",
       "gifts": "المستودع",

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

@@ -1543,8 +1543,8 @@
       "dashboard": "Dashboard",
       "roomsGroup": "Rooms Management",
       "roomsDashboard": "Rooms Dashboard",
-      "bookingSettings": "Booking Settings",
-      "bookings": "Room Bookings",
+      "bookingSettings": "Settings",
+      "bookings": "Bookings",
       "external": "External Meetings",
       "giftsGroup": "Gifts",
       "gifts": "Warehouse",

artifacts/tx-os/src/pages/protocol.tsx

@@ -1490,13 +1490,14 @@ export default function ProtocolPage() {
                         )}
                       />
                     </button>
-                    {open &&
-                      children.map(({ key: ck, label: cl, icon: CIcon }) => (
+                    {open && (
+                      <div className="flex md:flex-col gap-1 md:ms-4 md:border-s-2 md:border-slate-300 md:ps-1">
+                        {children.map(({ key: ck, label: cl, icon: CIcon }) => (
                           <button
                             key={ck}
                             onClick={() => setTab(ck)}
                             className={cn(
-                            "flex items-center gap-2 px-3 py-2 text-sm whitespace-nowrap transition-colors md:w-full md:justify-start md:ps-6",
+                              "flex items-center gap-2 px-3 py-2 text-sm whitespace-nowrap transition-colors md:w-full md:justify-start",
                               tab === ck
                                 ? "bg-sky-500 text-white"
                                 : "text-slate-600 hover:bg-slate-200",
@@ -1507,6 +1508,8 @@ export default function ProtocolPage() {
                           </button>
                         ))}
                       </div>
+                    )}
+                  </div>
                 );
               }
               if (key === "gifts") {
@@ -1538,13 +1541,14 @@ export default function ProtocolPage() {
                         )}
                       />
                     </button>
-                    {open &&
-                      children.map(({ key: ck, label: cl, icon: CIcon }) => (
+                    {open && (
+                      <div className="flex md:flex-col gap-1 md:ms-4 md:border-s-2 md:border-slate-300 md:ps-1">
+                        {children.map(({ key: ck, label: cl, icon: CIcon }) => (
                           <button
                             key={ck}
                             onClick={() => setTab(ck)}
                             className={cn(
-                            "flex items-center gap-2 px-3 py-2 text-sm whitespace-nowrap transition-colors md:w-full md:justify-start md:ps-6",
+                              "flex items-center gap-2 px-3 py-2 text-sm whitespace-nowrap transition-colors md:w-full md:justify-start",
                               tab === ck
                                 ? "bg-sky-500 text-white"
                                 : "text-slate-600 hover:bg-slate-200",
@@ -1555,6 +1559,8 @@ export default function ProtocolPage() {
                           </button>
                         ))}
                       </div>
+                    )}
+                  </div>
                 );
               }
               return (