Hide dashboard sidebar on staff/supervisor/admin sub-pages; fix mobile overflow

- Sidebar now shows only on each role's root landing page
  (/dashboard/staff, /dashboard/supervisor, /dashboard/admin) and hides on
  every sub-page beneath them, not just Reports. Navbar's "Dashboard" link
  always leads back to the role root.
- Fixed two dropdown panels (EventsDropdown, the Email/WhatsApp Attendees
  recipient picker) that could extend past the viewport's right edge on
  narrow screens; both now stretch to their trigger's width like other
  dropdowns in the app already do.
- Wrapped the Admin Cashup event-costs table in the same overflow-auto
  container every sibling table on that page already uses, so it scrolls
  horizontally on narrow screens instead of squeezing its columns.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/app/dashboard/admin/cashup/[id]/page.tsx

@@ -175,49 +175,51 @@ function CostsTab({ eventId, token, costs, eventOptions, isClosed, onChanged }:
 
       {isClosed && <div className="text-xs text-gray-500">This event is closed — costs can't be changed until it's reopened.</div>}
 
-      <table className="w-full text-sm">
-        <thead>
-          <tr className="text-left text-gray-500 border-b">
-            <th className="py-1">Label</th>
-            <th className="py-1">Type</th>
-            <th className="py-1">Ticket type</th>
-            <th className="py-1">Paid from</th>
-            <th className="py-1 text-right">Amount</th>
-            <th className="py-1 text-right">Total</th>
-            {!isClosed && <th className="py-1"></th>}
-          </tr>
-        </thead>
-        <tbody>
-          {costs.map(c => (
-            <tr key={c.id} className="border-b last:border-0">
-              <td className="py-1.5">{c.label}</td>
-              <td className="py-1.5">{c.costType === "once_off" ? "Once-off" : "Per item"}</td>
-              <td className="py-1.5">{c.eventOption?.name || "—"}</td>
-              <td className="py-1.5 capitalize">{c.paidFromMethod || "—"}</td>
-              <td className="py-1.5 text-right">{money(c.amount)}</td>
-              <td className="py-1.5 text-right font-medium">{money(c.total ?? c.amount)}</td>
-              {!isClosed && (
-                <td className="py-1.5 text-right whitespace-nowrap">
-                  <button className="text-xs text-indigo-600 hover:underline mr-2" onClick={() => startEdit(c)}>Edit</button>
-                  <button className="text-xs text-red-600 hover:underline" onClick={() => remove(c.id)}>Delete</button>
-                </td>
-              )}
+      <div className="overflow-auto">
+        <table className="w-full text-sm min-w-[600px]">
+          <thead>
+            <tr className="text-left text-gray-500 border-b">
+              <th className="py-1">Label</th>
+              <th className="py-1">Type</th>
+              <th className="py-1">Ticket type</th>
+              <th className="py-1">Paid from</th>
+              <th className="py-1 text-right">Amount</th>
+              <th className="py-1 text-right">Total</th>
+              {!isClosed && <th className="py-1"></th>}
             </tr>
-          ))}
-          {costs.length === 0 && (
-            <tr><td colSpan={7} className="py-3 text-gray-400 text-center">No costs added yet.</td></tr>
+          </thead>
+          <tbody>
+            {costs.map(c => (
+              <tr key={c.id} className="border-b last:border-0">
+                <td className="py-1.5">{c.label}</td>
+                <td className="py-1.5">{c.costType === "once_off" ? "Once-off" : "Per item"}</td>
+                <td className="py-1.5">{c.eventOption?.name || "—"}</td>
+                <td className="py-1.5 capitalize">{c.paidFromMethod || "—"}</td>
+                <td className="py-1.5 text-right">{money(c.amount)}</td>
+                <td className="py-1.5 text-right font-medium">{money(c.total ?? c.amount)}</td>
+                {!isClosed && (
+                  <td className="py-1.5 text-right whitespace-nowrap">
+                    <button className="text-xs text-indigo-600 hover:underline mr-2" onClick={() => startEdit(c)}>Edit</button>
+                    <button className="text-xs text-red-600 hover:underline" onClick={() => remove(c.id)}>Delete</button>
+                  </td>
+                )}
+              </tr>
+            ))}
+            {costs.length === 0 && (
+              <tr><td colSpan={7} className="py-3 text-gray-400 text-center">No costs added yet.</td></tr>
+            )}
+          </tbody>
+          {costs.length > 0 && (
+            <tfoot>
+              <tr>
+                <td colSpan={5} className="pt-2 text-right text-gray-500">Total costs</td>
+                <td className="pt-2 text-right font-semibold">{money(totalCosts)}</td>
+                {!isClosed && <td />}
+              </tr>
+            </tfoot>
           )}
-        </tbody>
-        {costs.length > 0 && (
-          <tfoot>
-            <tr>
-              <td colSpan={5} className="pt-2 text-right text-gray-500">Total costs</td>
-              <td className="pt-2 text-right font-semibold">{money(totalCosts)}</td>
-              {!isClosed && <td />}
-            </tr>
-          </tfoot>
-        )}
-      </table>
+        </table>
+      </div>
 
       {editingId !== null && (
         <div className="border rounded p-3 space-y-2 bg-gray-50">

frontend/src/app/dashboard/layout.tsx

@@ -63,10 +63,14 @@ export default function DashboardLayout({ children }: { children: React.ReactNod
     );
   }
 
-  // The Reports page is a full-width, self-contained workspace (its own header, filters, and
-  // navigation) — the dashboard sidebar's section links (My Events, Profile, Admin, etc.) would
-  // just crowd it, so it's hidden there specifically, not app-wide.
-  const hideSidebar = pathname === "/dashboard/supervisor/reports";
+  // Sub-pages within staff/supervisor/admin (e.g. /dashboard/supervisor/reports,
+  // /dashboard/admin/cashup/[id]) are full-width workspaces with their own internal navigation
+  // and header — the dashboard sidebar's section links (My Events, Profile, Admin, etc.) would
+  // just crowd them. The sidebar stays visible only on each role's root landing page; every
+  // deeper sub-page hides it. Navigating back is never a dead end: Navbar's "Dashboard" link is
+  // always present and /dashboard auto-redirects to the role root.
+  const SIDEBAR_ROOTS = ["/dashboard/staff", "/dashboard/supervisor", "/dashboard/admin"];
+  const hideSidebar = !!pathname && SIDEBAR_ROOTS.some(root => pathname !== root && pathname.startsWith(root + "/"));
 
   return (
     <div className="min-h-screen flex flex-col">

frontend/src/app/dashboard/supervisor/email-attendees/page.tsx

@@ -75,7 +75,7 @@ function AttendeesCheckboxDropdown({
         )}
       </button>
       {open && (
-        <div className="absolute z-10 mt-1 w-64 max-h-72 overflow-auto bg-white border rounded shadow">
+        <div className="absolute z-10 mt-1 left-0 right-0 max-h-72 overflow-auto bg-white border rounded shadow">
           <div className="px-3 py-2 border-b sticky top-0 bg-white space-y-1">
             <label className="text-sm flex items-center gap-2">
               <input type="checkbox" checked={allSelected} onChange={e => toggleAll(e.target.checked)} />

frontend/src/app/dashboard/supervisor/whatsapp-attendees/page.tsx

@@ -86,7 +86,7 @@ function AttendeesCheckboxDropdown({
         )}
       </button>
       {open && (
-        <div className="absolute z-10 mt-1 w-64 max-h-72 overflow-auto bg-white border rounded shadow">
+        <div className="absolute z-10 mt-1 left-0 right-0 max-h-72 overflow-auto bg-white border rounded shadow">
           <div className="px-3 py-2 border-b sticky top-0 bg-white space-y-1">
             <label className="text-sm flex items-center gap-2">
               <input type="checkbox" checked={allSelected} onChange={(e) => toggleAll(e.target.checked)} />

frontend/src/components/reports/EventsDropdown.tsx

@@ -42,7 +42,7 @@ export default function EventsDropdown({ options, value, onChange }: {
         <ChevronDown className={"w-4 h-4 text-gray-400 shrink-0 transition-transform " + (open ? "rotate-180" : "")} />
       </button>
       {open && (
-        <div className="absolute z-20 mt-1 w-full min-w-[240px] bg-white border rounded-lg shadow-lg max-h-64 overflow-auto p-1">
+        <div className="absolute z-20 mt-1 left-0 right-0 bg-white border rounded-lg shadow-lg max-h-64 overflow-auto p-1">
           <div className="flex items-center justify-between px-2 py-1.5 text-xs text-gray-500 border-b mb-1">
             <button type="button" className="hover:underline" onClick={() => onChange(options.map(o => o.value))}>Select all</button>
             <button type="button" className="hover:underline" onClick={() => onChange([])}>Clear</button>