[Fix] Emoji-triggered Slack tasks lose the reacted message

[roomote-roomote]

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

What changed

• Give reaction-triggered synthetic Slack turns a delivery identity separate from the reacted message timestamp.
• Include the reacted message text and files directly in the synthetic turn while excluding the embedded source from duplicate incremental context.
• Preserve the real Slack message timestamp for reactions and source metadata across active runs and snapshot resumes.

Why this change was made

Emoji-triggered continuations reused the reacted message timestamp as the current turn. The delivery tracker therefore excluded the actual message from thread context and could send only the configured trigger prompt to the agent.

Impact

Reacting with the configured Roomote emoji now gives the agent the message and attachments it was asked to act on, including in active and resumed task threads, without breaking reactions against the original Slack message.

[roomote-community]

No code issues found. See task

_{Reviewed 6024731}