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.

cron/scheduler.py

@@ -59,10 +59,13 @@ _HOME_TARGET_ENV_VARS = {
     "signal": "SIGNAL_HOME_CHANNEL",
     "mattermost": "MATTERMOST_HOME_CHANNEL",
     "sms": "SMS_HOME_CHANNEL",
+    "email": "EMAIL_HOME_ADDRESS",
+    "dingtalk": "DINGTALK_HOME_CHANNEL",
     "feishu": "FEISHU_HOME_CHANNEL",
     "wecom": "WECOM_HOME_CHANNEL",
     "weixin": "WEIXIN_HOME_CHANNEL",
     "bluebubbles": "BLUEBUBBLES_HOME_CHANNEL",
+    "qqbot": "QQ_HOME_CHANNEL",
 }
 
 from cron.jobs import get_due_jobs, mark_job_run, save_job_output, advance_next_run