docs(ai-chat): mark the latest changelog entry as the 4.5.0 GA release

Author: ericallam

docs/ai-chat/changelog.mdx

@@ -1,10 +1,10 @@
 ---
 title: "Changelog"
 sidebarTitle: "Changelog"
-description: "Pre-release updates for AI chat agents."
+description: "Changelog for the AI Agents SDK."
 ---
 
-<Update label="June 25, 2026" description="4.5.0-rc.8" tags={["SDK", "Bug fix"]}>
+<Update label="July 2, 2026" description="4.5.0" tags={["SDK", "Bug fix"]}>
 
 ## Point chat sessions at a different project or environment