The sync_positions loop only upserted positions from Alpaca but never
deleted DB rows for positions that were closed/liquidated on the broker
side. After a paper reset, the next sync would not remove the stale
positions because they simply weren't in Alpaca's response anymore.
Now performs full reconciliation: after upserting what Alpaca reports,
deletes any DB positions for the account that Alpaca no longer holds.
Workers (ingestion, parser, extractor, aggregation, recommendation,
broker, lake-publisher) now check the pipeline:enabled Redis flag on
each loop iteration and sleep when disabled.
The toggle endpoint flushes all pipeline queues on disable so queued
jobs don't resume when workers eventually check. Broker/trading queues
are excluded from flush to avoid dropping in-flight orders.
Celes Renata