[Fix] Discord automation replies disappear after task resume

[roomote-community]

Opened on behalf of Matt Rubens. Follow up by mentioning @roomote, in the web UI, or in Discord.

What changed

• Preserve Discord provider, channel, thread, and message metadata when tasks resume from the web app or preview proxy.
• Recover a missing automation thread from its saved report-root message and persist the returned Discord thread ID.
• Continue routing later updates into an existing thread without attempting nested thread creation.

Why this change was made

After the initial thread fix in #1012, a task with a saved report message but no thread could not persist a recovered thread. Web-driven snapshot resumes also dropped non-Slack communication metadata, which removed send_chat_reply from the resumed worker and made generic channel posting fall back to Slack.

Impact

Discord automation tasks retain their reply tool and destination after waking up. Partially bound reports can recover their real thread once, and subsequent updates stay in that thread.

[roomote-community]

No code issues found. See task

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