fix(thread): find thread title by id

All thread with or without thread type has a `a` node with id
`thread_subject`, the node is visible in 爱丽丝 style and invisible in
other styles.

This commit use the id to select thread title to fix title not found
exception. Seems server changed the style recently which breaks the
old implementation.

Author: realth000

lib/features/thread/bloc/thread_bloc.dart

@@ -265,29 +265,9 @@ class ThreadBloc extends Bloc<ThreadEvent, ThreadState> with LoggerMixin {
           threadDataNode,
           document.currentPage() ?? 1,
         );
-        String? title;
-        // Most threads have thread type node before the title.
-        title =
-            // Thread belongs to not types.
-            document
-                    .querySelector('div#postlist h1.ts > a:nth-child(1)')
-                    ?.nextNode
-                    ?.text
-                    ?.trim() ??
-                // Thread belongs to some type.
-                document
-                    .querySelector('div#postlist h1.ts > a:nth-child(1)')
-                    ?.innerText
-                    .trim();
-        if (title?.isEmpty ?? true) {
-          // Some thread belongs to no type.
-          title = document
-              .querySelector('div#postlist h1.ts')
-              ?.nodes
-              .elementAtOrNull(0)
-              ?.text
-              ?.trim();
-        }
+        // Title node ALWAYS has an `a` node with id `thread_subject`.
+        // It's invisible in most styles and visible in 爱丽丝 style.
+        final title = document.querySelector('a#thread_subject')?.text?.trim();
 
         final allLinksInBreadCrumb = document.querySelectorAll('div#pt a');
         final forumName = switch (allLinksInBreadCrumb.length < 2) {