Make all arr library-list fetches cache-first with live fallback

Every script that fetches the full Lidarr/Sonarr/Radarr tracked-library
list now goes through arr_get_tracked_data() instead of hitting the API
directly -- cache-first when fresh, live fetch as fallback when stale,
waits out an active rescan before either. Per-item file data (trackFile/
episodefile/moviefile) stays live-only everywhere, since that's the
actual disk-truth these scripts' decisions depend on and was never part
of what's cached.

Also adds arr_cache_prefill.sh to CRITICAL_MAINTENANCE_SCRIPTS (30min
tier) with a short 1min wait ceiling, so the cache stays consistently
fresh instead of only refreshing whenever some other script happens to
write through. A full cache refresh for all three arrs measured at ~12s
total live -- nothing like the multi-hour cost of an actual rescan.

Arrs_Stack/lidarr_cleanup.sh

@@ -299,15 +299,17 @@ check_arr_version "$LIDARR_URL" "$LIDARR_API_KEY" "v1" "$LIDARR_VERSION_MAJOR" "
 
 info "Querying Lidarr API..."
 
-# Fetch all artists
-ARTIST_RESPONSE=$(arr_api "$LIDARR_URL" "$LIDARR_API_KEY" "v1" "artist" "Lidarr") || {
+# Cache-first — arr_get_tracked_data() serves the shared cache when it's fresh (now kept
+# current every 30min by arr_cache_prefill.sh in CRITICAL_MAINTENANCE_SCRIPTS), falls back to
+# a live fetch when it's stale, and waits out an active rescan before either. Only the artist
+# list itself is cached — the per-artist trackFile data below is never cached and always live,
+# since that's the actual disk-truth this script's cleanup decisions depend on.
+ARTIST_RESPONSE=$(arr_get_tracked_data "lidarr" "$LIDARR_URL" "$LIDARR_API_KEY" "v1") || {
     error "Failed to fetch artists from Lidarr"
     notify "Lidarr cleanup failed on $(hostname) — could not fetch artists" \
         "Lidarr Cleanup" "warning"
     exit 1
 }
-# Write-through — free cache refresh from a fetch this script already needed.
-arr_cache_write "lidarr" "$ARTIST_RESPONSE"
 
 ARTIST_IDS=$(echo "$ARTIST_RESPONSE" | jq -r '.[].id' 2>/dev/null)
 ARTIST_COUNT=$(echo "$ARTIST_IDS" | grep -c "[0-9]" 2>/dev/null || echo 0)