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/arr_sync.sh

@@ -659,9 +659,20 @@ REMOTE
 
 _local_library() {
     local url="$1" api_key="$2" api_ver="$3" endpoint="$4"
-    curl -sf --max-time "$ARR_SYNC_API_TIMEOUT" \
-        -H "X-Api-Key: $api_key" \
-        "${url}/api/${api_ver}/${endpoint}" 2>/dev/null
+    # endpoint doubles as arr_type here — artist/series/movie match lidarr/sonarr/radarr's
+    # ARR_LIBRARY_ENDPOINT values exactly, so the same lookup works either direction.
+    local arr_type
+    case "$endpoint" in
+        artist) arr_type="lidarr" ;;
+        series) arr_type="sonarr" ;;
+        movie)  arr_type="radarr" ;;
+    esac
+    # Cache-first — arr_get_tracked_data() serves the shared cache when it's fresh (kept
+    # current every 30min by arr_cache_prefill.sh in CRITICAL_MAINTENANCE_SCRIPTS), falls back
+    # to a live fetch when it's stale, and waits out an active rescan before either. This is
+    # the LOCAL host's library only — the remote side of this sync isn't cached, since the
+    # shared cache is per-host by design.
+    arr_get_tracked_data "$arr_type" "$url" "$api_key" "$api_ver"
 }
 
 _local_defaults() {