fix(telegram): propagate extra base_url config

tests/gateway/test_config.py

@@ -551,6 +551,26 @@ class TestLoadGatewayConfig:
 
         assert config.platforms[Platform.TELEGRAM].extra["disable_link_previews"] is True
 
+    def test_bridges_telegram_extra_base_url_from_config_yaml(self, tmp_path, monkeypatch):
+        hermes_home = tmp_path / ".hermes"
+        hermes_home.mkdir()
+        config_path = hermes_home / "config.yaml"
+        config_path.write_text(
+            "telegram:\n"
+            "  extra:\n"
+            "    base_url: https://custom-proxy.example.com/bot\n",
+            encoding="utf-8",
+        )
+
+        monkeypatch.setenv("HERMES_HOME", str(hermes_home))
+
+        config = load_gateway_config()
+
+        assert (
+            config.platforms[Platform.TELEGRAM].extra["base_url"]
+            == "https://custom-proxy.example.com/bot"
+        )
+
     def test_bridges_notice_delivery_from_config_yaml(self, tmp_path, monkeypatch):
         hermes_home = tmp_path / ".hermes"
         hermes_home.mkdir()