feat(search): publisher_filter for the media search endpoint

Adds publisher_filter to SearchMediaItems/SearchMediaItemsUnified
(fuzzy word_similarity against mi.publisher, mirroring genre_filter),
plumbs it through services.SearchParams and the search handler, and
extends the GREATEST relevance ranking to include publisher matches.
Serves the app's author/publisher/genre/tag click-through browses
(UX pass item 5 — publisher was the only facet without a server
filter).

internal/handlers/media.go

@@ -2133,6 +2133,7 @@ func (mh *MediaHandler) SearchMediaItems(c *echo.Context) error {
 	authorFilter := c.QueryParam("author_filter")
 	seriesFilter := c.QueryParam("series_filter")
 	genreFilter := c.QueryParam("genre_filter")
+	publisherFilter := c.QueryParam("publisher_filter")
 	tagsFilter := c.QueryParam("tags_filter")
 	languageFilter := c.QueryParam("language_filter")
 	yearMin, _ := strconv.Atoi(c.QueryParam("year_min"))
@@ -2152,20 +2153,21 @@ func (mh *MediaHandler) SearchMediaItems(c *echo.Context) error {
 
 	// Build search params
 	params := services.SearchParams{
-		UserID:         userID.ID,
-		LibraryID:      libUUID,
-		SearchQuery:    query,
-		AuthorFilter:   authorFilter,
-		SeriesFilter:   seriesFilter,
-		GenreFilter:    genreFilter,
-		TagsFilter:     tagsFilter,
-		LanguageFilter: languageFilter,
-		YearMin:        yearMin,
-		YearMax:        yearMax,
-		HasCover:       pgtype.Bool{Bool: hasCover, Valid: hasCoverValid},
-		Sort:           sortParam,
-		Limit:          limit,
-		Offset:         offset,
+		UserID:          userID.ID,
+		LibraryID:       libUUID,
+		SearchQuery:     query,
+		AuthorFilter:    authorFilter,
+		SeriesFilter:    seriesFilter,
+		GenreFilter:     genreFilter,
+		PublisherFilter: publisherFilter,
+		TagsFilter:      tagsFilter,
+		LanguageFilter:  languageFilter,
+		YearMin:         yearMin,
+		YearMax:         yearMax,
+		HasCover:        pgtype.Bool{Bool: hasCover, Valid: hasCoverValid},
+		Sort:            sortParam,
+		Limit:           limit,
+		Offset:          offset,
 	}
 
 	c.Logger().Info("SearchMediaItems called",