fix(ui): hide Comic/Manga editor section for non-comics media

The metadata editor's Comic/Manga section (Manga Type, Reading
Direction, Age Rating, Story Arc, Imprint, Scan Info, Metadata
Notes, B&W) rendered for every item — an audiobook showed a manga
dropdown, which is nonsense.

MediaDetail now carries LibraryTypeName (resolved via
GetLibraryType in the /media/:uuid handler) and a
ShowComicMetadata() gate: comics and manga libraries always show the
section; other media only when the scanner recorded comic-style
values (fixed-layout manga-style EPUBs get those scanner defaults
deliberately — when present they stay editable).

internal/router/frontend.go

@@ -1712,6 +1712,12 @@ func registerFrontendRoutes(cfg *Config) {
 		}
 
 		// Assemble response (no field duplication!)
+		libraryTypeName := ""
+		if lib, lerr := cfg.Queries.GetLibrary(c.Request().Context(), mediaItem.LibraryID); lerr == nil {
+			if lt, terr := cfg.Queries.GetLibraryType(c.Request().Context(), lib.LibraryTypeID); terr == nil {
+				libraryTypeName = lt.Name
+			}
+		}
 		detail := handlers.MediaDetail{
 			MediaItems:         mediaItem, // Embedded - ALL fields available
 			FileLocation:       fileLocation,
@@ -1720,6 +1726,7 @@ func registerFrontendRoutes(cfg *Config) {
 			Collections:        collections,
 			ReadingProgress:    progress,
 			BookStats:          bookStats,
+			LibraryTypeName:    libraryTypeName,
 			ActiveConflict:     activeConflict,
 			NotesCount:         len(notes),
 			HighlightsCount:    len(highlights),