feat: add generic tmux TUI testing infrastructure with Claude Code and #5453

Job	Run time
build-and-check	2m 27s
test-sdk	43s
test-packages/agent-runtime	1m 0s
test-packages/billing	44s
test-common	38s
test-.agents	42s
test-integration-packages/internal	40s
test-web	49s
test-cli	1m 9s
test-packages/internal	47s
test-integration-common	42s
test-integration-.agents	38s
test-integration-packages/agent-runtime	40s
test-integration-sdk	45s
test-integration-web	46s
test-integration-cli	35s
test-integration-packages/billing	40s
	14m 25s

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