fix(instances): add missing TOOL_NAME variable to compose template

The compose template uses {{TOOL_NAME}} for container_name but
we weren't passing it in the variables dict, causing YAML parse error.

Error was:
yaml: cannot use 'map[string]interface {}{"TOOL_NAME":interface {}(nil)}' as a map key

apps/api/src/api/tool_instances.py

@@ -148,6 +148,7 @@ async def create_instance(
             "REPO_PATH": repo.path,
             "INSTANCE_NAME": instance_name,
             "INSTANCE_ID": instance_name,
+            "TOOL_NAME": instance_name,
             "TOOL_PORT": tool_port,
             "USER_ID": str(user_id),
             "PROJECT_ID": str(project_id),