merge: resolve conflicts for S3 storage branch with main

Integrates S3/MinIO storage backend with structured logging changes
from main. Both boto3 and apscheduler retained in requirements.txt.

.env.example

@@ -52,3 +52,9 @@ STORAGE_BACKEND=local
 # When USE_CACHE=true: check database for cached responses before making API calls
 # When USE_CACHE=false: always make fresh API calls (still stores results in database)
 USE_CACHE=true
+
+# ---- Webhooks ----
+
+# Comma-separated list of webhook URLs for job completion and alert notifications
+# Supports generic HTTP POST and Slack/Discord incoming webhooks
+# WEBHOOK_URLS=https://hooks.slack.com/services/XXX,https://example.com/webhook