Creates AND (optionally) publishes a post to one of the user's own connected posting platforms, in a single call. This is the ONLY operation needed for posting — legacy /collab/content/* endpoints are not exposed here. BEFORE calling this, find the user's available channel(s) (e.g. via "list_channels") and, if there is more than one, ask the user which to use. For platform, use "telegram" unless the user explicitly asks about Instagram or Threads. Gather from the user: the caption/text they want (or an idea/topic if they want you to write it), whether they want an AI-generated image attached ("generateImage": true) or no image at all, and when it should go out — "immediate" to publish it right now (this call will trigger the actual publish before returning), "manual" with an "eventAt" ISO datetime to schedule it for a specific time, "next_slot" to drop it into the account's next free auto-posting slot, or "draft" to just save it without publishing so it can be edited/sent later. If "generateImage" is true, this call will synchronously generate the image before returning (can take up to ~30s) and attach it to the post. The response tells you exactly what happened: "content" is the saved post, "imageGenerated"/"imageError" report the image step, and "published"/"publishError" report whether it was actually sent out immediately. If publishing fails (e.g. platform not ready), tell the user and suggest they check their channel connection.