feat: Add customer management, payments, and push notifications with security enhancements

Major Feature Additions:
- Customer management: Full CRUD with data export and privacy compliance
- Payment management: Centralized payment tracking and administration
- Push notification subscriptions: Manage and track web push subscriptions

Security Enhancements:
- IP whitelist middleware for administrative endpoints
- Data retention service with configurable policies
- Enhanced push notification security documentation
- Security fixes progress tracking (2025-11-14)

UI/UX Improvements:
- Enhanced navigation with improved mobile responsiveness
- Updated admin dashboard with order status counts
- Improved product CRUD forms
- New customer and payment management interfaces

Backend Improvements:
- Extended customer service with data export capabilities
- Enhanced order service with status count queries
- Improved crypto payment service with better error handling
- Updated validators and configuration

Documentation:
- DEPLOYMENT_NGINX_GUIDE.md: Nginx deployment instructions
- IP_STORAGE_ANALYSIS.md: IP storage security analysis
- PUSH_NOTIFICATION_SECURITY.md: Push notification security guide
- UI_UX_IMPROVEMENT_PLAN.md: Planned UI/UX enhancements
- UI_UX_IMPROVEMENTS_COMPLETED.md: Completed improvements

Cleanup:
- Removed temporary database WAL files
- Removed stale commit message file

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

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

LittleShop/wwwroot/js/pwa.js

@@ -102,9 +102,13 @@ class PWAManager {
         installBtn.id = 'pwa-install-btn';
         installBtn.className = 'btn btn-primary btn-sm';
         installBtn.innerHTML = '<i class="fas fa-download"></i> Install App';
+        // Detect if mobile bottom nav exists and adjust positioning
+        const isMobileView = window.innerWidth < 768;
+        const bottomPosition = isMobileView ? '80px' : '20px'; // 80px to clear mobile bottom nav
+
         installBtn.style.cssText = `
             position: fixed;
-            bottom: 20px;
+            bottom: ${bottomPosition};
             right: 20px;
             z-index: 1000;
             box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
@@ -242,9 +246,13 @@ class PWAManager {
         installBtn.id = 'pwa-install-btn';
         installBtn.className = 'btn btn-primary btn-sm';
         installBtn.innerHTML = '<i class="fas fa-mobile-alt"></i> Install as App';
+        // Detect if mobile bottom nav exists and adjust positioning
+        const isMobileView = window.innerWidth < 768;
+        const bottomPosition = isMobileView ? '80px' : '20px'; // 80px to clear mobile bottom nav
+
         installBtn.style.cssText = `
             position: fixed;
-            bottom: 20px;
+            bottom: ${bottomPosition};
             right: 20px;
             z-index: 1000;
             box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);