fix(whatsapp): resolve LID↔phone aliases in allowlist matching (#3830)

WhatsApp DMs can arrive with LID sender IDs even when
WHATSAPP_ALLOWED_USERS is configured with phone numbers. The allowlist
check now reads bridge session mapping files (lid-mapping-*.json) to
resolve phone↔LID aliases, matching users regardless of which
identifier format the message uses.

Both the Python gateway (_is_user_authorized) and the Node bridge
(allowlist.js) now share the same mapping-file-based resolution logic.

Co-authored-by: Frederico Ribeiro <fr@tecompanytea.com>

tests/gateway/test_unauthorized_dm_behavior.py

@@ -3,6 +3,7 @@ from unittest.mock import AsyncMock, MagicMock
 
 import pytest
 
+import gateway.run as gateway_run
 from gateway.config import GatewayConfig, Platform, PlatformConfig
 from gateway.platforms.base import MessageEvent
 from gateway.session import SessionSource
@@ -62,6 +63,32 @@ def _make_runner(platform: Platform, config: GatewayConfig):
     return runner, adapter
 
 
+def test_whatsapp_lid_user_matches_phone_allowlist_via_session_mapping(monkeypatch, tmp_path):
+    _clear_auth_env(monkeypatch)
+    monkeypatch.setenv("WHATSAPP_ALLOWED_USERS", "15550000001")
+    monkeypatch.setattr(gateway_run, "_hermes_home", tmp_path)
+
+    session_dir = tmp_path / "whatsapp" / "session"
+    session_dir.mkdir(parents=True)
+    (session_dir / "lid-mapping-15550000001.json").write_text('"900000000000001"', encoding="utf-8")
+    (session_dir / "lid-mapping-900000000000001_reverse.json").write_text('"15550000001"', encoding="utf-8")
+
+    runner, _adapter = _make_runner(
+        Platform.WHATSAPP,
+        GatewayConfig(platforms={Platform.WHATSAPP: PlatformConfig(enabled=True)}),
+    )
+
+    source = SessionSource(
+        platform=Platform.WHATSAPP,
+        user_id="900000000000001@lid",
+        chat_id="900000000000001@lid",
+        user_name="tester",
+        chat_type="dm",
+    )
+
+    assert runner._is_user_authorized(source) is True
+
+
 @pytest.mark.asyncio
 async def test_unauthorized_dm_pairs_by_default(monkeypatch):
     _clear_auth_env(monkeypatch)