feat: instruct agent to clone repos at runtime instead of relying on pre-cloned image

Repos are no longer pre-cloned in the Docker image so the agent always
reviews against the latest code.

Author: jesseturner21

.github/scripts/prompts/review.md

@@ -2,7 +2,11 @@ Review this GitHub PR: {pr_url}
 
 You have tools to fetch the PR diff, read files, search the web, and post comments on the PR.
 
-You have these repos cloned locally for context:
+First, clone the repos you'll need for context:
+- git clone https://github.com/aws/agentcore-cli.git /opt/workspace/agentcore-cli
+- git clone https://github.com/aws/agentcore-l3-cdk-constructs.git /opt/workspace/agentcore-l3-cdk-constructs
+
+Then use these local repos for context:
 - /opt/workspace/agentcore-cli — aws/agentcore-cli
 - /opt/workspace/agentcore-l3-cdk-constructs — aws/agentcore-l3-cdk-constructs