Refactor: Streamline product management UI and enhance PWA behavior

**Product List Improvements:**
- Move Import/Export to settings menu for cleaner interface
- Replace Edit/Variants/Multi-Buys buttons with single Details action
- Remove Blazor UI button from product list
- Simplify product row actions for better mobile UX

**Product Details Enhancements:**
- Add Danger Zone section with Delete button at bottom
- Improve visual hierarchy and action placement

**Navigation Updates:**
- Remove hamburger menu toggle (desktop nav always visible)
- Rename Settings to Menu in mobile bottom nav
- Update settings drawer header and icon

**Code Cleanup:**
- Remove unused Blazor, Variations, and Variants endpoints (243 lines)
- Consolidate variant/multi-buy management within product details
- Clean up ProductsController for better maintainability

**PWA & Notifications:**
- Add proper PWA support detection (only show if browser supports)
- Implement session-based notification prompt tracking
- Prevent repeated prompts after dismissal in same session
- Respect permanent dismissal preferences
- Enhance iOS Safari detection and instructions

**Technical Details:**
- 6 files changed, 96 insertions(+), 286 deletions(-)
- Build successful with 0 errors
- All features production-ready

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

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

LittleShop/Areas/Admin/Views/Shared/_Layout.cshtml

@@ -46,9 +46,6 @@
                 <a class="navbar-brand" href="@Url.Action("Index", "Dashboard", new { area = "Admin" })">
                     <i class="fas fa-store"></i> TeleShop Admin
                 </a>
-                <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target=".navbar-collapse">
-                    <span class="navbar-toggler-icon"></span>
-                </button>
                 <div class="navbar-collapse collapse d-sm-inline-flex justify-content-between">
                     <ul class="navbar-nav flex-grow-1">
                         <li class="nav-item">
@@ -178,8 +175,8 @@
             </li>
             <li class="mobile-nav-item">
                 <a href="#" class="mobile-nav-link" onclick="toggleSettingsDrawer(); return false;">
-                    <i class="fas fa-cog"></i>
-                    <span>Settings</span>
+                    <i class="fas fa-bars"></i>
+                    <span>Menu</span>
                 </a>
             </li>
         </ul>
@@ -189,7 +186,7 @@
     <div class="drawer-overlay" onclick="toggleSettingsDrawer()"></div>
     <div class="settings-drawer" id="settingsDrawer">
         <div class="settings-drawer-header">
-            <h5>Settings</h5>
+            <h5>Menu</h5>
             <button class="settings-drawer-close" onclick="toggleSettingsDrawer()">
                 <i class="fas fa-times"></i>
             </button>
@@ -243,6 +240,24 @@
                     System Settings
                 </a>
             </li>
+            <li class="settings-menu-item">
+                <hr class="dropdown-divider">
+            </li>
+            <li class="settings-menu-item">
+                <a href="@Url.Action("Import", "Products", new { area = "Admin" })" class="settings-menu-link">
+                    <i class="fas fa-upload"></i>
+                    Import Products
+                </a>
+            </li>
+            <li class="settings-menu-item">
+                <a href="@Url.Action("Export", "Products", new { area = "Admin" })" class="settings-menu-link">
+                    <i class="fas fa-download"></i>
+                    Export Products
+                </a>
+            </li>
+            <li class="settings-menu-item">
+                <hr class="dropdown-divider">
+            </li>
             <li class="settings-menu-item">
                 <form method="post" action="@Url.Action("Logout", "Account", new { area = "Admin" })">
                     <button type="submit" class="settings-menu-link" style="width: 100%; border: none; background: none; text-align: left;">