refactor(utils): one PgTextString for the four pgtype.Text unwrappers

handlers textToString, router textToString, router getText, and utils
normText were four copies of the same NULL-to-empty unwrap (99 call
sites). One exported utils.PgTextString replaces them all; the private
normText (comparison normalizer) stays but is now the odd one out.

Harness fix found on the way: setupTestServer built a full wiring
literal for route registration and then RETURNED a second, sparser
literal that never copied AnnotationService — setup.AnnotationService
was always nil on the struct every test receives. Nobody noticed until
cross_library_move_test became the first caller (it previously used
the now-retired plain CreateMediaHighlight query); it now exercises
the real SaveHighlight path through the wired service.

internal/router/reader.go

@@ -80,21 +80,21 @@ func registerReaderRoutes(cfg *Config) {
 		mediaUUID, _ := uuid.FromBytes(mediaItem.ID.Bytes[0:16])
 		libUUID, _ := uuid.FromBytes(mediaItem.LibraryID.Bytes[0:16])
 		metadata := templates.ReaderMetadata{
-			MediaItemID:      mediaUUID.String(),
-			Title:            mediaItem.Title,
-			Author:           textToString(mediaItem.Author),
+			MediaItemID: mediaUUID.String(),
+			Title:       mediaItem.Title,
+			Author:      utils.PgTextString(mediaItem.Author),
 			// Sidecar covers store a raw library-relative path; resolve to
 			// the cookie-authed /uploads URL (idempotent for items whose
 			// stored value is already a servable path).
 			CoverImagePath:   utils.ResolveMediaURL(mediaItem.LibraryID, mediaItem.CoverImagePath),
 			LibraryType:      mediaItem.FormatGroup,
-			MimeType:         textToString(mediaItem.MimeType),
+			MimeType:         utils.PgTextString(mediaItem.MimeType),
 			FilePath:         mediaItem.FilePath,
 			TotalPages:       int(mediaItem.PageCount.Int32),
 			ChapterCount:     int(mediaItem.ChapterCount.Int32),
 			FormatGroup:      mediaItem.FormatGroup,
-			MangaType:        textToString(mediaItem.MangaType),
-			ReadingDirection: textToString(mediaItem.ReadingDirection),
+			MangaType:        utils.PgTextString(mediaItem.MangaType),
+			ReadingDirection: utils.PgTextString(mediaItem.ReadingDirection),
 			LibraryID:        libUUID.String(),
 			FileURL:          utils.ResolveMediaURL(mediaItem.LibraryID, pgtype.Text{String: mediaItem.FilePath, Valid: true}),
 			TotalCharacters:  mediaItem.TotalCharacters.Int64,