fix(ui): clear text selection on tap anywhere in the article

Every block of the dictionary article was wrapped in its own
SelectionContainer, so a tap in one block never cleared a highlight
held in another. A single container now wraps the article list — a tap
anywhere clears the selection and selection can span adjacent blocks.

app/src/main/java/com/example/research/ui/article/ArticleScreen.kt

@@ -123,14 +123,11 @@ fun ArticleContent(
             val isHeavyArticle =
                 articleState.dslContent.size > HEAVY_ARTICLE_BLOCK_COUNT
 
+            val articleList: @Composable (Modifier) -> Unit = { listModifier ->
                 LazyColumn(
                     state = listState,
                     contentPadding = PaddingValues(top = Spacing.listItemVertical),
-                modifier = modifier
-                    .fillMaxSize()
-                    .onSizeChanged { viewportSize = it }
-                    .windowInsetsPadding(AppWindowInsets.horizontalSafeDrawing)
-                    .padding(end = 16.dp)
+                    modifier = listModifier
                         .testTag("article_content")
                         .semantics {
                             testTagsAsResourceId = true
@@ -169,12 +166,19 @@ fun ArticleContent(
                                 )
                             }
                         }
-                    if (isHeavyArticle) {
                         textContent()
+                    }
+                }
+            }
+            val articleListModifier = modifier
+                .fillMaxSize()
+                .onSizeChanged { viewportSize = it }
+                .windowInsetsPadding(AppWindowInsets.horizontalSafeDrawing)
+                .padding(end = 16.dp)
+            if (isHeavyArticle) {
+                articleList(articleListModifier)
             } else {
-                        SelectionContainer { textContent() }
-                    }
-                }
+                SelectionContainer { articleList(articleListModifier) }
             }
         }
         is ArticleState.Error -> {