release: merge latest.json platforms across split mac/linux releases

So a per-machine release (macOS here, Linux on Arch) of the same version keeps
both platform entries instead of clobbering the one not built this run.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/release-gitea.mjs

@@ -100,15 +100,30 @@ async function main() {
   for (const [key, { file, sig }] of Object.entries(updater)) {
     platforms[key] = { signature: sig, url: dlUrl(verTag, path.basename(file)) };
   }
+
+  // Merge with the currently-published latest.json so a split release (e.g. macOS
+  // on one machine, Linux on another) doesn't drop the platform we didn't build
+  // this run — as long as both build the SAME version. A published older version
+  // is ignored (a fresh version starts clean; the other platform re-publishes).
+  let merged = platforms;
+  try {
+    const cur = await fetch(dlUrl(UPDATER_TAG, 'latest.json')).then((r) => (r.ok ? r.json() : null));
+    if (cur && cur.version === VERSION && cur.platforms) {
+      const kept = Object.keys(cur.platforms).filter((k) => !platforms[k]);
+      merged = { ...cur.platforms, ...platforms };
+      if (kept.length) console.log('Merged kept platforms from published latest.json:', kept.join(', '));
+    }
+  } catch { /* offline / first ever release */ }
+
   const latest = {
     version: VERSION,
     notes: `X-Plane Cockpit ${verTag}`,
     pub_date: new Date().toISOString(),
-    platforms,
+    platforms: merged,
   };
   const latestPath = path.join(ROOT, 'desktop/latest.json');
   fs.writeFileSync(latestPath, JSON.stringify(latest, null, 2));
-  console.log('latest.json platforms:', Object.keys(platforms).join(', ') || '(none)');
+  console.log('latest.json platforms:', Object.keys(merged).join(', ') || '(none)');
 
   // Upload latest.json to the fixed "updater" release (constant endpoint URL).
   const upd = await ensureRelease(UPDATER_TAG, 'Updater channel', 'Rolling pointer used by the in-app updater.');