fix: report webhook redirects as failures instead of silent success

[namann5]

Description

Fixes #1739

\send_webhook()\ in
otification_service.py\ was validating webhook redirect targets against the SSRF blocklist but never actually following them or reporting failure. With \ollow_redirects=False, the payload was never delivered to the final URL � yet the function returned (True, None), silently reporting success.

This means any webhook endpoint that returns a 3xx redirect causes security notifications to be silently dropped with no indication to the user.

Change

The redirect handler now returns (False, error_message)\ for all redirect outcomes instead of falling through to
eturn True, None:

Scenario	Before	After
Redirect to blocked IP	(False, "Redirect to blocked IP range: ...")\	? Same (unchanged)
Redirect to allowed IP	? (True, None)\ � silent failure	? (False, "Webhook returned HTTP 302 redirect to ..., payload not delivered")\
Redirect with empty Location header	? (True, None)\ � silent failure	? (False, "Webhook returned HTTP 302 with no Location header, payload not delivered")\
Redirect with relative URL (no hostname)	? (True, None)\ � silent failure	? (False, "Webhook returned HTTP 301 redirect with no hostname: ..., payload not delivered")\
Unresolvable redirect target	(False, "Could not resolve redirect target: ...")\	? Same (unchanged)

Testing

Added 3 new tests:

• \ est_send_webhook_redirect_to_allowed_ip_reports_failure\ � redirect to a non-blocked IP returns (False, ...)\
• \ est_send_webhook_redirect_empty_location\ � 3xx with no Location header returns (False, ...)\
• \ est_send_webhook_redirect_relative_location\ � 3xx with relative URL returns (False, ...)\

All 35 existing notification tests continue to pass.

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