fix: pipeline stop now halts all workers and flushes queues

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.

services/aggregation/main.py

@@ -23,6 +23,7 @@ from services.shared.logging import inject_trace_context, setup_logging
 from services.shared.redis_keys import (
     QUEUE_AGGREGATION,
     QUEUE_RECOMMENDATION,
+    is_pipeline_enabled,
     queue_key,
 )
 
@@ -134,6 +135,10 @@ async def main() -> None:
 
     try:
         while True:
+            if not await is_pipeline_enabled(redis_client):
+                await asyncio.sleep(1)
+                continue
+
             raw = await redis_client.lpop(queue)
             if raw is None:
                 await asyncio.sleep(1)