OPDS Flattening (#1904)

* Flattening OPDS Structure

# Changed
- Flattened OPDS structure to reduce user taps.

* Fixing format

* Fixing book series titles

* Optimized file size to use pre-calculated data to avoid an I/O touch.

* Fixes #1898 by aligning all content headers to the correct MIME types

* Remove dead code

* Fixed a bug with continue point where it fails on chapters or volumes tagged with a range

---------

Co-authored-by: Robbie Davis <robbie@therobbiedavis.com>

API/Services/SeriesService.cs

@@ -466,10 +466,14 @@ public class SeriesService : ISeriesService
                 if (string.IsNullOrEmpty(title)) return;
                 volume.Name += $" - {title}";
             }
-            else
+            else if (volume.Name != "0")
             {
                 volume.Name += $" - {firstChapter.TitleName}";
             }
+            else
+            {
+                volume.Name += $"";
+            }
 
             return;
         }