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_release_fixer.sh

@@ -302,13 +302,13 @@ echo "━━━ $ICON_SYNC Fetching artist paths ━━━"
 declare -A ARTIST_PATH_CACHE
 declare -A ARTIST_NAME_CACHE
 
-ALL_ARTISTS=$(lidarr_api "artist") || {
+# Cache-first — arr_get_tracked_data() serves the shared cache when it's fresh (now kept
+# current every 30min by arr_cache_prefill.sh in CRITICAL_MAINTENANCE_SCRIPTS), falls back to
+# a live fetch when it's stale, and waits out an active rescan before either.
+ALL_ARTISTS=$(arr_get_tracked_data "lidarr" "$LIDARR_URL" "$LIDARR_API_KEY" "v1") || {
     error "Failed to fetch artists"
     exit 1
 }
-# Write-through — keeps the shared tracked-data cache fresh as a side effect of a fetch
-# this script already needed for its own purposes. See arr_get_tracked_data() in common.sh.
-arr_cache_write "lidarr" "$ALL_ARTISTS"
 
 while IFS= read -r artist; do
     aid=$(echo "$artist" | jq -r '.id')