WIP: restore database migration system and improve error handling

- Restore runMigrations functionality for database schema migrations
- Remove indexedDBMigrationService.ts (was for IndexedDB to SQLite migration)
- Recreate migrationService.ts and db-sql/migration.ts for schema management
- Add proper TypeScript error handling with type guards in AccountViewView
- Fix CreateAndSubmitClaimResult property access in QuickActionBvcBeginView
- Remove LeafletMouseEvent from Vue components array (it's a type, not component)
- Add null check for UserNameDialog callback to prevent undefined assignment
- Implement extractErrorMessage helper function for consistent error handling
- Update router to remove database-migration route

The migration system now properly handles database schema evolution
across app versions, while the IndexedDB to SQLite migration service
has been removed as it was specific to that one-time migration.

src/components/DataExportSection.vue

@@ -141,10 +141,6 @@ export default class DataExportSection extends Vue {
           result,
         ) as unknown as Contact[];
       }
-      // if (USE_DEXIE_DB) {
-      //   await db.open();
-      //   allContacts = await db.contacts.toArray();
-      // }
 
       // Convert contacts to export format
       const exportData = contactsToExportJson(allContacts);