Enable OpenCode Zen for minimax + kimi; add buffbench agents #6534

Job	Run time
build-and-check	2m 29s
test-integration-packages/billing	59s
test-integration-packages/internal	1m 10s
test-integration-common	52s
test-integration-cli	51s
test-integration-sdk	1m 18s
test-integration-web	39s
test-integration-packages/agent-runtime	43s
test-.agents	43s
test-packages/internal	55s
test-packages/billing	45s
test-web	1m 15s
test-sdk	46s
test-packages/agent-runtime	45s
test-common	38s
test-cli	51s
	15m 39s

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