fix: Update all navigation links to point to new admin import system

PROBLEM FIXED:
- Main menu "Import" was still pointing to old unified-import system
- Dashboard quick actions pointed to broken import routes
- Keyboard shortcut Alt+I was routing to old system

NAVIGATION UPDATES:
✅ Desktop/Mobile nav menu: /import → /admin/import
✅ Dashboard quick action button: /import → /admin/import
✅ Dashboard "Open Import" link: /import → /admin/import
✅ Keyboard shortcut Alt+I: /import → /admin/import
✅ Support modal page mapping: /import → /admin/import
✅ Base template page names: /import → /admin/import

ADMIN PERMISSIONS:
- Import menu items now properly hidden by default
- Shown only to admin users via JavaScript permission check
- Maintains security for admin-only functionality

REMOVED REFERENCES:
- All /flexible route references (old flexible import system)
- Cleaned up navigation menu from removed functionality

NOW WORKING:
- Clicking "Import" in main menu → new /admin/import interface
- Alt+I keyboard shortcut → new /admin/import interface
- Dashboard import button → new /admin/import interface
- All navigation properly secured for admin users only

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

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

templates/support_modal.html

@@ -206,7 +206,7 @@ let supportSystem = {
             '/files': 'File Cabinet',
             '/financial': 'Financial/Ledger',
             '/documents': 'Document Management',
-            '/import': 'Data Import',
+            '/admin/import': 'Data Import',
             '/search': 'Advanced Search',
             '/admin': 'System Administration'
         };