Fix "Show next" staleness bug; add location/date/share-QR to manage overlay

Two changes, bundled since they landed in the same session and touch
overlapping files:

1. Fix: "Show next" sent the browser's full queue snapshot to
   POST /api/queue/reorder, which hard-rejected if the server's queue
   had shifted since the last fetch (e.g. right after a queue-length
   trim). New POST /api/queue/promote moves one photo to the front
   authoritatively, with no dependency on client staleness. /reorder
   itself is now tolerant too -- unrecognized IDs are dropped and
   missing ones appended, instead of rejecting the whole request.

2. Feature: the manage button's overlay now also shows the photo's
   location (top-left, only if Immich reverse-geocoded it from GPS
   EXIF), the date it was taken (bottom-right), and a QR code (bottom-
   left) linking to a 30-minute public Immich share link -- created
   lazily when someone actually scans it, not when the button's
   pressed. New server endpoints GET /frame/photo-info and
   GET /frame/share/{asset_id} (scoped to the frame's current/queued
   photos, not any arbitrary Immich asset). Firmware-side, the overlay
   mechanism generalizes from one spliced region to up to four
   (manage_qr_overlay.c), each its own small buffer, still never
   holding the full frame in RAM.

server/app/templates/index.html

@@ -224,12 +224,21 @@
       persistOrder(items);
     }
 
-    function showNext(index) {
-      const items = upcomingItems.slice();
-      const [moved] = items.splice(index, 1);
-      items.unshift(moved);
-      renderUpcoming(items);
-      persistOrder(items);
+    async function showNext(index) {
+      const assetId = upcomingItems[index].id;
+      try {
+        const resp = await fetch('/api/queue/promote', {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ asset_id: assetId }),
+        });
+        if (!resp.ok) {
+          throw new Error(await resp.text());
+        }
+      } catch (e) {
+        showStatus(false, e.message);
+      }
+      loadQueue(); // always refetch the authoritative order rather than guessing locally
     }
 
     async function persistOrder(items) {