SIENTIAPDE-2012: per-group levels/ignore_models_id filtering

Extends filter_notification_alerts (slot_manager.py) and
filter_notification_reports (formatters.py) to check
receiver_group.get('levels') and receiver_group.get('ignore_models_id'),
mirroring the existing contents/ignore pattern exactly. Closes the gap
SIENTIAPDE-2011 deliberately left open: the query-time union/intersection
filter widens what gets fetched for the union of all active groups, but until
now nothing narrowed each group back down to its own configured slice.

Both checks short-circuit via `not levels_list or ...` / `not
ignore_models_id_list or ...` rather than accessing notification['level']/
['model_id'] directly, so groups that don't configure either field (today's
common case, and every existing unit test fixture) never evaluate the
right-hand side and can't raise KeyError on notifications missing those keys.
ignore_models_id reads via `.get(...) or []`, defensively handling an
explicit `null` in a receiver_groups document from the start (same fix
SIENTIAPDE-2011 needed a follow-up commit for).

Tests:
- 8 new unit tests (4 per file): levels restriction, ignore_models_id
  restriction, neither-configured passthrough, explicit-None safety.
- New e2e test (test_scenario_a_2_1_per_group_levels_and_ignore_models_id)
  against real Mongo/Redis/Temporal: two active groups configured
  differently: SIENTIAPDE-2011's query-time filter widens the fetch to the
  union of both, and this subtask's per-group filter narrows each group back
  to its own levels/ignore_models_id, including the case where a model is
  ignored by only one of the active groups.
- Deduplicated the two e2e suites' identical _extract_html_body helper into
  e2e/helpers.py (extract_html_body), now shared by both.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

e2e/helpers.py

@@ -7,6 +7,7 @@ import json
 import re
 import uuid
 from datetime import UTC, datetime, timedelta
+from email.message import EmailMessage, Message
 from pathlib import Path
 from typing import Any
 
@@ -356,3 +357,40 @@ def default_receiver_group(
         'contents': contents or ['core_alerts', 'persistent_alerts', 'reports'],
         'ignore_models_id': ignore_models_id or [],
     }
+
+
+def extract_html_body(message: EmailMessage | Message) -> str:
+    """
+    Return the text/html portion of an email message as a decoded string.
+
+    Walks every part looking for the first text/html payload, decoding it
+    according to the part's transfer encoding and charset. Falls back to
+    the message's own ``get_content``/raw payload when no HTML part is
+    present so callers can still inspect plain-text reports. Shared between
+    the Alerts and Reports e2e suites, both of which send mail through the
+    same ``build_email_html``/``send_email`` activities.
+
+    Args:
+        message: Captured email message returned by the test SMTP server.
+
+    Return:
+        str: HTML body content, or an empty string when nothing decodable
+            is found.
+    """
+    if message.is_multipart():
+        for part in message.walk():
+            if part.get_content_type() != 'text/html':
+                continue
+            payload = part.get_payload(decode=True)
+            if payload is None:
+                continue
+            charset = part.get_content_charset() or 'utf-8'
+            return payload.decode(charset, errors='replace')
+    payload = message.get_payload(decode=True)
+    if payload is not None:
+        charset = message.get_content_charset() or 'utf-8'
+        return payload.decode(charset, errors='replace')
+    try:
+        return message.get_content()
+    except (AttributeError, KeyError):
+        return str(message.get_payload() or '')