feat(device-sync): overhaul Device Sync page

- New two-panel layout with live album search (search3, 300ms debounce)
  and 10 random albums when search is empty — replaces full paginated load
- Pre-sync summary modal: shows files to add/delete, net change, available
  space; Proceed button disabled when space is insufficient
- calculate_sync_payload now filters already-synced tracks (path exists on
  device) so add_bytes/add_count reflect the true delta
- Space check accounts for pending deletions: addBytes > availableBytes + delBytes
- Separate deviceSyncJobStore for ephemeral job progress state
- Removable drive detection + auto-poll every 5 s via sysinfo
- Desired-state diff: de-selecting a synced source stages it for deletion
  instead of silently removing it
- Status badges (Synced / Pending / Deletion) with matching row highlights
- Live-Search badge (⚡) and Zufallsalben section label (⇌) in album browser
- Status summary row height aligned with search field (52 px)
- i18n: all new keys added to all 8 locales (en/de/fr/nl/nb/zh/ru/es)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/styles/layout.css

@@ -912,6 +912,13 @@
   background: color-mix(in srgb, var(--accent) 20%, transparent);
 }
 
+/* ─── Sidebar device-sync queue ─── */
+.sidebar-sync-queue {
+  background: color-mix(in srgb, var(--success, #4ade80) 10%, var(--bg-sidebar));
+  border-color: color-mix(in srgb, var(--success, #4ade80) 25%, transparent);
+  color: var(--success, #4ade80);
+}
+
 @keyframes spin-slow {
   to { transform: rotate(360deg); }
 }