fix(ui): tag counts, j/k nav, stream layout, search alignment

- Tag rail counts now reflect cards-only when in cards view
  (ListTags accepts cardsOnly filter, JS passes it per view)
- j/k navigation scoped to visible (intent/search filtered) list
- scrollSelectedIntoView works in both stream and cards view
- Entity items wrap title/desc/preview in .entity-content flex
  container so tags/pills align right consistently
- Title no longer eaten by description/body (flex-shrink + min-width)
- Search bar centered in header with margin auto
- switchView awaits loadEntities+loadTags to fix stale intent counts

internal/api/tags.go

@@ -13,7 +13,8 @@ type TagResponse struct {
 
 func listTags(store *db.Store) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		tags, err := store.ListTags()
+		cardsOnly := r.URL.Query().Get("cards_only") == "true"
+		tags, err := store.ListTags(cardsOnly)
 		if err != nil {
 			writeInternalError(w, err)
 			return