chore(release): 0.4.0 (#141)

Breaking release for the new Conversation, Message, PromptInput, Panel,
attachments, media, activity, and MessageParts families. Removes the old
chat components and documents their replacements.

Author: TheGreatAxios

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@corbits/react-ui",
-  "version": "0.3.2",
+  "version": "0.4.0",
   "description": "React components for agent and workflow surfaces.",
   "keywords": [
     "agents",