perf(zxdb): server-render index pages with ISR and initial data

Why
- Reduce time-to-first-content on ZXDB index pages by eliminating the initial client-side fetch and enabling incremental static regeneration.

What
- Main Explorer (/zxdb):
  - Server-renders first page of results and lookup lists (genres, languages, machinetypes) and passes them as initial props.
  - Keeps client interactivity for subsequent searches/filters.
- Labels index (/zxdb/labels):
  - Server-renders first page of empty search and passes as initial props to skip the first fetch.
- Category lists:
  - Genres (/zxdb/genres), Languages (/zxdb/languages), Machine Types (/zxdb/machinetypes) now server-render their lists and export revalidate=3600.
  - Refactored list components to accept server-provided items; removed on-mount fetching.
- Links & prefetch:
  - Replaced remaining anchors with Next Link to enable prefetch where applicable.

Tech details
- Added revalidate=3600 to the index pages for ISR.
- Updated ZxdbExplorer to accept initial results and initial filter lists; skips first client fetch when initial props are present.
- Updated LabelsSearch to accept initial payload and skip first fetch in default state.
- Updated GenreList, LanguageList, MachineTypeList to be presentational components receiving items from server pages.

Notes
- Low-churn list APIs already emit Cache-Control for CDN; list pages now render instantly from server.
- Further polish (breadcrumbs, facet counts UI) can build on this foundation without reintroducing initial network waits.

Signed-off-by: Junie@lucy.xalior.com

src/app/zxdb/page.tsx

@@ -1,5 +1,5 @@
 import ZxdbExplorer from "./ZxdbExplorer";
-import { searchEntries } from "@/server/repo/zxdb";
+import { searchEntries, listGenres, listLanguages, listMachinetypes } from "@/server/repo/zxdb";
 
 export const metadata = {
   title: "ZXDB Explorer",
@@ -9,6 +9,18 @@ export const revalidate = 3600;
 
 export default async function Page() {
   // Server-render initial page (no query) to avoid first client fetch
-  const initial = await searchEntries({ page: 1, pageSize: 20, sort: "id_desc" });
-  return <ZxdbExplorer initial={initial as any} />;
+  const [initial, genres, langs, machines] = await Promise.all([
+    searchEntries({ page: 1, pageSize: 20, sort: "id_desc" }),
+    listGenres(),
+    listLanguages(),
+    listMachinetypes(),
+  ]);
+  return (
+    <ZxdbExplorer
+      initial={initial as any}
+      initialGenres={genres as any}
+      initialLanguages={langs as any}
+      initialMachines={machines as any}
+    />
+  );
 }