Add disabled OpenCode Zen provider scaffold #6505

Job	Run time
build-and-check	3m 18s
test-integration-packages/internal	1m 10s
test-integration-packages/billing	1m 27s
test-integration-common	51s
test-integration-cli	51s
test-integration-web	1m 2s
test-packages/agent-runtime	56s
test-integration-packages/agent-runtime	1m 5s
test-cli	1m 10s
test-packages/billing	1m 2s
test-common	56s
test-integration-sdk	2m 10s
test-sdk	1m 2s
test-.agents	59s
test-web	1m 22s
test-packages/internal	1m 1s
	20m 22s

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