Improve UX with navigation, attendance management, and calendar fixes

## Quick Wins
- **AdminSidebar**: Move "View Public Site" to clickable logo area
- **Plans**: Fix layout to center single plan, dynamic grid for multiple
- **AdminGallery**: Add empty state message with "Create Event" button

## Event Attendance Enhancement
- **NEW: AdminEventAttendance page** with full-featured table view:
  - Tab filters (All/Yes/No/Maybe RSVPs)
  - Search by name/email
  - Bulk selection with Select All
  - Individual attendance toggle buttons (merged column)
  - CSV export functionality (client requirement)
  - Summary statistics cards
- **AdminEvents**: Navigate to new attendance page instead of dialog
- **App.js**: Add /admin/events/:eventId/attendance route

## Calendar Fixes
- **MemberCalendar**: Add state management for navigation (date/view)
  - Fix non-functional buttons (Today/Back/Next/Month/Week/Day/Agenda)
  - Add onNavigate and onView handlers
- **NEW: MemberCalendar.css**: Extract styles from broken jsx syntax
  - Fix toolbar button styling and interactivity

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/components/AdminSidebar.js

@@ -265,7 +265,7 @@ const AdminSidebar = ({ isOpen, onToggle, isMobile }) => {
       >
         {/* Header */}
         <div className="flex items-center justify-between p-4 border-b border-[#ddd8eb]">
-          <div className="flex items-center gap-3">
+          <Link to="/" className="flex items-center gap-3 group flex-1 min-w-0">
             <img
               src={`${process.env.PUBLIC_URL}/loaf-logo.png`}
               alt="LOAF Logo"
@@ -274,11 +274,16 @@ const AdminSidebar = ({ isOpen, onToggle, isMobile }) => {
               }`}
             />
             {isOpen && (
-              <h2 className="text-xl font-semibold text-[#422268]" style={{ fontFamily: "'Inter', sans-serif" }}>
-                Admin
-              </h2>
+              <div className="flex-1 min-w-0">
+                <h2 className="text-xl font-semibold text-[#422268]" style={{ fontFamily: "'Inter', sans-serif" }}>
+                  Admin
+                </h2>
+                <p className="text-xs text-[#664fa3] group-hover:text-[#ff9e77] transition-colors" style={{ fontFamily: "'Nunito Sans', sans-serif" }}>
+                  View Public Site
+                </p>
+              </div>
             )}
-          </div>
+          </Link>
           <button
             onClick={onToggle}
             className="p-2 rounded-lg hover:bg-[#DDD8EB]/20 transition-colors"