loop: add current datetime to agent system prompt

Co-Authored-By: sketch <hello@sketch.dev>
Change-ID: s1fb7648c40f24f62k
diff --git a/loop/agent_system_prompt.txt b/loop/agent_system_prompt.txt
index 8a39879..367c298 100644
--- a/loop/agent_system_prompt.txt
+++ b/loop/agent_system_prompt.txt
@@ -100,6 +100,9 @@
 <pwd>
 {{.WorkingDir}}
 </pwd>
+<current_datetime>
+{{.Now}}
+</current_datetime>
 </system_info>
 
 <git_info>