fix: floating bookmarks

- update floating bookmarks
- fix search suggestions
- fix filters

backend/apps/books/serializers.py

@@ -3,6 +3,7 @@ from rest_framework import serializers
 import logging
 
 from apps.books.models import Book, BookChapter, EBook, ReadingProgress, ReadingStatus, DownloadRecord
+from apps.books.services.ebook_metadata import subjects_from_ebook
 from apps.books.services.metadata import enrich_ebook_metadata
 from apps.books.services.process_ebook import apply_processing_to_ebook
 from apps.reader.models import ReadingSettings
@@ -71,14 +72,18 @@ class EBookListSerializer(serializers.ModelSerializer):
     format = serializers.CharField(read_only=True)
     progress = serializers.SerializerMethodField()
     started = serializers.SerializerMethodField()
+    subjects = serializers.SerializerMethodField()
 
     class Meta:
         model = EBook
         fields = [
             "id", "title", "author", "filename", "format", "page_count", "file_size",
-            "cover_image", "created_at", "progress", "started",
+            "cover_image", "created_at", "progress", "started", "subjects",
         ]
 
+    def get_subjects(self, obj: EBook) -> list[str]:
+        return subjects_from_ebook(obj)
+
     def get_progress(self, obj):
         try:
             return obj.reading_progress.current_position