Crawlee's SessionPool throws 'Could not find SDK_SESSION_POOL_STATE.json'
when initializing against a freshly-created isolated storage dir.
Setting CRAWLEE_PURGE_ON_START=1 tells Crawlee to start fresh instead
of trying to load non-existent session state — fixes FS.com and ATGBICS
crashes at the start of every 2h cycle after the dirs were cleaned up.
148d2e1000