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/dashboard.html

@@ -129,7 +129,7 @@
                             <span class="font-medium">Global Search</span>
                             <kbd class="text-xs text-neutral-500 dark:text-neutral-400 mt-1">Ctrl+F</kbd>
                         </button>
-                        <button onclick="window.location.href='/import'" class="w-full flex flex-col items-center justify-center p-4 bg-neutral-50 dark:bg-neutral-900/50 hover:bg-neutral-100 dark:hover:bg-neutral-900 rounded-lg border border-neutral-200 dark:border-neutral-700 transition-colors duration-200">
+                        <button onclick="window.location.href='/admin/import'" class="w-full flex flex-col items-center justify-center p-4 bg-neutral-50 dark:bg-neutral-900/50 hover:bg-neutral-100 dark:hover:bg-neutral-900 rounded-lg border border-neutral-200 dark:border-neutral-700 transition-colors duration-200">
                             <i class="fa-solid fa-cloud-arrow-up text-2xl text-primary-600 mb-1"></i>
                             <span class="font-medium">Import Data</span>
                             <kbd class="text-xs text-neutral-500 dark:text-neutral-400 mt-1">Alt+I</kbd>
@@ -325,7 +325,7 @@ async function loadRecentImports() {
             <div>
                 <div class="flex items-center justify-between mb-2">
                     <h6 class="text-sm font-semibold flex items-center gap-2"><i class="fa-solid fa-file-arrow-up"></i> Recent Import Status</h6>
-                    <a href="/import" class="text-primary-600 hover:underline text-sm">Open Import</a>
+                    <a href="/admin/import" class="text-primary-600 hover:underline text-sm">Open Import</a>
                 </div>
                 <div class="border border-neutral-200 dark:border-neutral-700 rounded-lg p-3">${items || '<p class="text-neutral-500 text-sm">No imported data yet.</p>'}</div>
                 <div class="mt-2 text-xs text-neutral-600 dark:text-neutral-400">Total records across tracked CSVs: <strong>${Number(total).toLocaleString()}</strong></div>