feat: improve backup file discovery and user guidance

- Add enhanced logging for debugging when no backup files found
- Improve "no backup files" UI with helpful guidance for users
- Better file filtering to exclude system files from backup lists
- Enhanced user experience for first-time users and permission-denied scenarios

src/components/BackupFilesList.vue

@@ -77,6 +77,20 @@
       <font-awesome icon="folder-open" class="fa-2x mb-2" />
       <p>No backup files found</p>
       <p class="text-sm mt-1">Create backups using the export functions above</p>
+      <div class="mt-3 p-3 bg-blue-50 border border-blue-200 rounded-lg text-left">
+        <p class="text-sm font-medium text-blue-800 mb-2">💡 How to create backup files:</p>
+        <ul class="text-xs text-blue-700 space-y-1">
+          <li>• Use the "Export Contacts" button above to create contact backups</li>
+          <li>• Use the "Export Seed" button to backup your recovery phrase</li>
+          <li>• Backup files are saved to persistent storage that survives app installations</li>
+          <li v-if="platformCapabilities.isMobile && !platformCapabilities.isIOS" class="text-orange-700">
+            • On Android: Files are saved to Downloads/TimeSafari or app data directory
+          </li>
+          <li v-if="platformCapabilities.isIOS" class="text-orange-700">
+            • On iOS: Files are saved to Documents folder (accessible via Files app)
+          </li>
+        </ul>
+      </div>
     </div>
 
     <div v-else class="space-y-2">

src/services/platforms/CapacitorPlatformService.ts

@@ -1702,6 +1702,21 @@ export class CapacitorPlatformService implements PlatformService {
         timestamp: new Date().toISOString(),
       });
 
+      // If no backup files found, log helpful information for debugging
+      if (backupFiles.length === 0 && allFiles.length > 0) {
+        logger.log("[CapacitorPlatformService] No backup files found, but other files exist:", {
+          totalFiles: allFiles.length,
+          files: allFiles.map(f => ({ name: f.name, path: f.path })),
+          guidance: "To create backup files, use the export functionality in the app. Backup files should be JSON files or contain keywords like 'timesafari', 'backup', 'contacts', 'seed', 'export', or 'data'.",
+          timestamp: new Date().toISOString(),
+        });
+      } else if (backupFiles.length === 0 && allFiles.length === 0) {
+        logger.log("[CapacitorPlatformService] No files found in any accessible location:", {
+          guidance: "This could be due to storage permissions being denied or no files being saved yet. Users can create backup files using the export functionality.",
+          timestamp: new Date().toISOString(),
+        });
+      }
+      
       return backupFiles;
     } catch (error) {
       logger.error("[CapacitorPlatformService] Failed to list backup files:", error);