[REQUEST] Support posting to threads in Slack tools.

[soichisumi]

Is your feature request related to a problem? Please describe. Currently, the Slack tool appears to only support posting to specific channels within linked accounts.

Describe the solution you'd like An option to allow the AI agent to post to threads is required.

Additional context Posting long messages directly to a Slack channel may be considered spam. We want users to post long messages within threads instead.