refactor(hash-conflicts): one usage-counts reader for the API and SSR surfaces

The pending-hash-conflict walk existed twice (JSON admin API emitting
numeric counts, SSR page emitting a formatted summary) — deliberately
different shapes, but both duplicated the counts-or-zero lookup and
the five-field total. MediaItemUsageCountsTotal is the shared read;
the per-surface shaping stays local on purpose.

internal/router/frontend.go

@@ -1214,11 +1214,7 @@ func registerFrontendRoutes(cfg *Config) {
 			}
 
 			for _, mi := range items {
-				counts, err := cfg.Queries.GetMediaItemUsageCounts(c.Request().Context(), mi.ID)
-				if err != nil {
-					counts = database.GetMediaItemUsageCountsRow{}
-				}
-				totalData := counts.ProgressCount + counts.HighlightsCount + counts.BookmarksCount + counts.NotesCount + counts.CollectionsCount
+				counts, totalData := handlers.MediaItemUsageCountsTotal(c.Request().Context(), cfg.Queries, mi.ID)
 				conflict.Items = append(conflict.Items, templates.HashConflictItemData{
 					ID:       uuid.UUID(mi.ID.Bytes).String(),
 					Title:    mi.Title,