fix(search): drop the open article when the query is cleared

app/src/main/java/com/example/research/feature/search/SearchViewModel.kt

@@ -122,6 +122,7 @@ class SearchViewModel(
             SearchAction.ClearQuery -> {
                 mutableSearchQuery.value = ""
                 savedStateHandle[KEY_SEARCH_QUERY] = ""
+                clearArticle()
             }
             is SearchAction.ArticleClicked -> {
                 articleHistory.clear()
@@ -136,6 +137,9 @@ class SearchViewModel(
     fun onSearchQueryChanged(query: String) {
         val sanitized = query.sanitizeQuery().trim()
         mutableSearchQuery.value = sanitized
+        if (sanitized.isBlank()) {
+            clearArticle()
+        }
         // Debounce SavedStateHandle writes to reduce disk I/O
         debounceSaveQueryJob?.cancel()
         debounceSaveQueryJob = viewModelScope.launch {