domain: flip last missed catalog .type reader (movies page) to .kind

library/movies/+page.svelte handleItemClick still read item.type === "Folder"
(missed in the phase-2a sweep). Now item.kind === "folder". Final sweep
confirms zero catalog .type/runTimeTicks/primaryImageTag/playbackPositionTicks
reads remain anywhere in src/.

Decision on dropping the dual-carry legacy Rust fields: KEPT. They are now
internal-only (no frontend reader), but internal Rust still depends on
item_type (SQL WHERE item_type='Audio', player audio filter, player-queue
passthrough) and the DB stores ticks. Removing them needs a DB/query-layer
migration with real regression risk and zero frontend benefit — out of scope
for the frontend-model goal, which is met.

Frontend 626, check clean.

src/routes/library/movies/+page.svelte

@@ -56,7 +56,7 @@
   });
 
   function handleItemClick(item: MediaItem) {
-    if (item.type === "Folder") {
+    if (item.kind === "folder") {
       goto(`/library/${item.id}`);
     } else {
       // Movies play directly.