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/immich_client.py

@@ -2,6 +2,8 @@
 
 from __future__ import annotations
 
+from datetime import datetime, timedelta, timezone
+
 import httpx
 
 
@@ -69,3 +71,36 @@ class ImmichClient:
         )
         resp.raise_for_status()
         return resp.content, resp.headers.get("content-type", "image/jpeg")
+
+    def get_asset(self, asset_id: str) -> dict:
+        """Full asset metadata, including embedded exifInfo (location,
+        capture date) -- used for the manage-button overlay's location/
+        date-taken text."""
+        resp = httpx.get(f"{self.base_url}/api/assets/{asset_id}", headers=self._headers, timeout=10)
+        resp.raise_for_status()
+        return resp.json()
+
+    def create_share_link(self, asset_id: str, expires_in_s: int) -> str:
+        """Creates a public, view-only Immich share link for a single
+        asset, expiring expires_in_s seconds from now, and returns its
+        public URL. Used by the manage-button overlay's share QR --
+        created lazily (only when someone actually scans it), not when
+        the button's pressed, so the expiry clock starts when it's
+        actually used."""
+        expires_at = (datetime.now(timezone.utc) + timedelta(seconds=expires_in_s)).isoformat()
+        resp = httpx.post(
+            f"{self.base_url}/api/shared-links",
+            headers=self._headers,
+            json={
+                "type": "INDIVIDUAL",
+                "assetIds": [asset_id],
+                "expiresAt": expires_at,
+                "allowUpload": False,
+                "allowDownload": True,
+                "showMetadata": True,
+            },
+            timeout=10,
+        )
+        resp.raise_for_status()
+        key = resp.json()["key"]
+        return f"{self.base_url}/share/{key}"