arr_full_rescan.sh, arr_cache_prefill.sh, and arr_rescan_monitor.sh were
missing the standard SAFEGUARDS header section other Arrs_Stack/Tools
scripts have. Also: arr_cache_prefill.sh now checks for an active rescan
before fetching, instead of doing a live fetch that arr_cache_write()
would just refuse to persist anyway -- avoids wasted API calls every
30min during a long rescan. arr_rescan_monitor.sh was also missing an
actual root check despite writing cache files; added it to match
convention rather than just document a safeguard that wasn't there.
Shared cache/rescan-duration logic in common.sh now takes an arr_type
param instead of being Lidarr-specific, so Sonarr and Radarr cleanup
scripts get the same cache-first fetch + rescan-aware retry Lidarr had.
Avoids redundant full-library API calls across scripts run back to back,
and stops false failures when a fetch lands mid-rescan.
Gmer4Lfe