move system-prompt/ to agent-runtime #3932

Job	Run time
build-and-check	2m 23s
test-backend	51s
test-npm-app	37s
test-.agents	31s
test-packages/agent-runtime	28s
test-common	27s
test-cli	33s
test-web	30s
test-integration-web	30s
test-integration-cli	28s
test-integration-common	28s
test-integration-packages/agent-runtime	28s
test-integration-backend	35s
test-integration-npm-app	26s
test-integration-.agents	27s
	9m 42s

Provide feedback