feat(cron+tests): extend origin fallback to email/dingtalk/qqbot + fix Weixin test mocks

Cron origin fallback extension (builds on #9193's _HOME_TARGET_ENV_VARS):
adds the three remaining origin-fallback-eligible platforms that have
home channel env vars configured in gateway/config.py but use non-generic
env var names:

- email    → EMAIL_HOME_ADDRESS   (non-standard suffix)
- dingtalk → DINGTALK_HOME_CHANNEL
- qqbot    → QQ_HOME_CHANNEL      (non-standard prefix: QQ_ not QQBOT_)

Picks up the completeness intent of @Xowiek's PR #11317 using the
architecturally-correct dict-based lookup from #9193, so platforms with
non-standard env var names actually resolve instead of silently missing.
Extended the parametrized regression test to cover the new three.

Weixin test mock alignment (builds on #10091's _send_session split):
Three test sites added in Batch 1 (TestWeixinSendImageFileParameterName)
and Batch 3 (TestWeixinVoiceSending) mocked only adapter._session, but
#10091 switched the send paths to check self._send_session. Added the
companion setter so the tests stay green with the session split in place.

tests/cron/test_scheduler.py

@@ -71,9 +71,12 @@ class TestResolveDeliveryTarget:
             ("signal", "SIGNAL_HOME_CHANNEL", "+15551234567"),
             ("mattermost", "MATTERMOST_HOME_CHANNEL", "team-town-square"),
             ("sms", "SMS_HOME_CHANNEL", "+15557654321"),
+            ("email", "EMAIL_HOME_ADDRESS", "home@example.com"),
+            ("dingtalk", "DINGTALK_HOME_CHANNEL", "cidNNN"),
             ("feishu", "FEISHU_HOME_CHANNEL", "oc_home"),
             ("wecom", "WECOM_HOME_CHANNEL", "wecom-home"),
             ("weixin", "WEIXIN_HOME_CHANNEL", "wxid_home"),
+            ("qqbot", "QQ_HOME_CHANNEL", "group-openid-home"),
         ],
     )
     def test_origin_delivery_without_origin_falls_back_to_supported_home_channels(
@@ -88,10 +91,13 @@ class TestResolveDeliveryTarget:
             "SIGNAL_HOME_CHANNEL",
             "MATTERMOST_HOME_CHANNEL",
             "SMS_HOME_CHANNEL",
+            "EMAIL_HOME_ADDRESS",
+            "DINGTALK_HOME_CHANNEL",
             "BLUEBUBBLES_HOME_CHANNEL",
             "FEISHU_HOME_CHANNEL",
             "WECOM_HOME_CHANNEL",
             "WEIXIN_HOME_CHANNEL",
+            "QQ_HOME_CHANNEL",
         ):
             monkeypatch.delenv(fallback_env, raising=False)
         monkeypatch.setenv(env_var, chat_id)