fix: preserve search input and add choseong lookup

src/MBN_STOCK_WEBVIEW.LegacyApplication/LegacyParityStockSearchService.cs

@@ -63,7 +63,14 @@ public sealed class LegacyParityStockSearchService : ILegacyStockLookup
         }
 
         var masterCatalog = await GetMasterCatalogAsync(cancellationToken).ConfigureAwait(false);
-        var searchTerm = query.ToUpper(CultureInfo.CurrentCulture);
+        var isInitialSearch = HangulSearchMatcher.IsInitialConsonantQuery(query);
+        // Keep the candidate set identical to the legacy provider searches.
+        // In particular, NXT search joins the online tables while the complete
+        // identity master intentionally does not. The master must therefore
+        // never be used as the visible result set for an initial-only query.
+        var searchTerm = isInitialSearch
+            ? string.Empty
+            : query.ToUpper(CultureInfo.CurrentCulture);
         var names = new List<string>();
 
         foreach (var profile in Profiles)
@@ -77,7 +84,10 @@ public sealed class LegacyParityStockSearchService : ILegacyStockLookup
             AppendNames(table, profile.SearchTableName, names);
         }
 
-        return new LegacyStockSearchData(query, names, masterCatalog);
+        var displayNames = isInitialSearch
+            ? names.Where(name => HangulSearchMatcher.IsMatch(name, query))
+            : names;
+        return new LegacyStockSearchData(query, displayNames, masterCatalog);
     }
 
     private async Task<IReadOnlyList<LegacyStockIdentity>> GetMasterCatalogAsync(