chore: commit pending ZXDB explorer changes prior to index perf work

Context
- Housekeeping commit to capture all current ZXDB Explorer work before index-page performance optimizations.

Includes
- Server-rendered entry detail page with ISR and parallelized DB queries.
- Node runtime for ZXDB API routes and params validation updates for Next 15.
- ZXDB repository extensions (facets, label queries, category queries).
- Cross-linking and Link-based prefetch across ZXDB UI.
- Cache headers on low-churn list APIs.

Notes
- Follow-up commit will focus specifically on speeding up index pages via SSR initial data and ISR.

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

src/app/zxdb/ZxdbExplorer.tsx

@@ -1,6 +1,7 @@
 "use client";
 
 import { useEffect, useMemo, useState } from "react";
+import Link from "next/link";
 
 type Item = {
   id: number;
@@ -156,7 +157,7 @@ export default function ZxdbExplorer() {
                   <tr key={it.id}>
                     <td>{it.id}</td>
                     <td>
-                      <a href={`/zxdb/entries/${it.id}`}>{it.title}</a>
+                      <Link href={`/zxdb/entries/${it.id}`}>{it.title}</Link>
                     </td>
                     <td>{it.machinetypeId ?? "-"}</td>
                     <td>{it.languageId ?? "-"}</td>
@@ -190,10 +191,10 @@ export default function ZxdbExplorer() {
 
       <hr />
       <div className="d-flex flex-wrap gap-2">
-        <a className="btn btn-sm btn-outline-secondary" href="/zxdb/labels">Browse Labels</a>
-        <a className="btn btn-sm btn-outline-secondary" href="/zxdb/genres">Browse Genres</a>
-        <a className="btn btn-sm btn-outline-secondary" href="/zxdb/languages">Browse Languages</a>
-        <a className="btn btn-sm btn-outline-secondary" href="/zxdb/machinetypes">Browse Machines</a>
+        <Link className="btn btn-sm btn-outline-secondary" href="/zxdb/labels">Browse Labels</Link>
+        <Link className="btn btn-sm btn-outline-secondary" href="/zxdb/genres">Browse Genres</Link>
+        <Link className="btn btn-sm btn-outline-secondary" href="/zxdb/languages">Browse Languages</Link>
+        <Link className="btn btn-sm btn-outline-secondary" href="/zxdb/machinetypes">Browse Machines</Link>
       </div>
     </div>
   );