Implement a "Create Post" screen for an Android social-media app using Jetpack Compose. The screen must contain a multiline TextField where the user can type a post, a live character counter, and a "Post" button. The counter changes color based on the current length: green for 0–200 characters, yellow for 201–260, and red for 261–280. The Post button is enabled only when the text is non-empty and the length is ≤ 280 characters; otherwise it is disabled. While the user types, display the remaining characters (280 − current length) and update the counter color immediately. The TextField should use maxLines = 5 and accept keyboard actions. Survive configuration changes (rotation) without losing text or color state. No external dependencies beyond standard Compose libraries are allowed.