UI simplification: remove redundant pages, reorganize Quick Actions

Phase 2 UI Cleanup:
- Delete empty programs/[id]/settings page
- Delete redundant projects/[id]/assignments page (use round-level management)
- Delete unused /users redirect directory
- Remove Settings button from program detail page
- Reorganize Round Quick Actions into visual groups (Project Management, Round Management)

Note: Mentor inline assignment deferred - the existing mentor page has
complex AI suggestion functionality that would need careful refactoring.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/app/(admin)/admin/programs/[id]/page.tsx

@@ -18,7 +18,7 @@ import {
   TableHeader,
   TableRow,
 } from '@/components/ui/table'
-import { ArrowLeft, Pencil, Plus, Settings } from 'lucide-react'
+import { ArrowLeft, Pencil, Plus } from 'lucide-react'
 import { formatDateOnly } from '@/lib/utils'
 
 interface ProgramDetailPageProps {
@@ -64,20 +64,12 @@ export default async function ProgramDetailPage({ params }: ProgramDetailPagePro
             </p>
           </div>
         </div>
-        <div className="flex gap-2">
-          <Button variant="outline" asChild>
-            <Link href={`/admin/programs/${id}/edit`}>
-              <Pencil className="mr-2 h-4 w-4" />
-              Edit
-            </Link>
-          </Button>
-          <Button variant="outline" asChild>
-            <Link href={`/admin/programs/${id}/settings`}>
-              <Settings className="mr-2 h-4 w-4" />
-              Settings
-            </Link>
-          </Button>
-        </div>
+        <Button variant="outline" asChild>
+          <Link href={`/admin/programs/${id}/edit`}>
+            <Pencil className="mr-2 h-4 w-4" />
+            Edit
+          </Link>
+        </Button>
       </div>
 
       {program.description && (