Fix progress sync: match server schema for authors and chapter

- authors: changed from string to array (server expects []string)
- chapter: removed (server expects *int, not a title string)

main.lua

@@ -666,9 +666,9 @@ function Bookhoard:collectBookData()
     local file_path = self.ui.document.file
 
     local title = props.display_title or ""
-    local authors = ""
+    local authors = {}
     if props.authors then
-        authors = props.authors
+        authors = { props.authors }
     end
 
     local file_sha256 = self:getFileSHA256()
@@ -679,18 +679,12 @@ function Bookhoard:collectBookData()
     local page = self.ui:getCurrentPage()
     local total_pages = self.ui.document:getPageCount()
 
-    local chapter = ""
-    if self.ui.toc and self.ui.toc.getTocTitleOfCurrentPage then
-        chapter = self.ui.toc:getTocTitleOfCurrentPage() or ""
-    end
-
     local book_data = {
         uuid = book_uuid,
         sha256 = file_sha256,
         title = title,
         authors = authors,
         percentage = percentage,
-        chapter = chapter,
         epubcfi = progress,
         page = page,
         total_pages = total_pages,