Set release date

Author: dargilco

sdk/ai/azure-ai-projects/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## 1.0.0 (Unreleased)
+## 1.0.0 (2025-07-31)
 
 First stable version of the client library. The client library now uses version `v1` of the
 AI Foundry [data plane REST APIs](https://aka.ms/azsdk/azure-ai-projects/ga-rest-api-reference).