Add silent flag on Command to suppress stdout/stderr from assistant messages

[jackcbrown89]

Summary

• Add silent?: boolean to Command (server) and silent: bool = False to CommandInterface (Python client).
• In invocation-runner.ts, when command.silent === true, skip the onStdout/onStderr handlers that would otherwise forward command output as assistant_message text_blocks. Applies to pre/post-agent commands and runCommandsOnly.

Compatibility

• Default silent is false/unset, so existing behaviour is unchanged.
• Older Python clients that don't send the field: server treats as not-silent (current behaviour).
• Older runtimes that don't read the field: behaviour unchanged.

Test plan

• npx vitest run in packages/runtimeuse — 145 passed (includes two new tests covering silent for pre/post commands and runCommandsOnly)
• uv run pytest --ignore=test/llm --ignore=test/sandbox --ignore=test/e2e in packages/runtimeuse-client-python — 44 passed
• e2e tests against a deployed runtime

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Note

Medium Risk
Adds a new wire-level silent field that changes how command stdout/stderr is streamed as assistant_messages, which could affect consumers relying on that output. Default behavior remains unchanged when the flag is unset/false, limiting compatibility risk.

Overview
Adds a per-command silent flag to both the TypeScript runtime Command type and the Python client CommandInterface to allow suppressing command stdout/stderr from being forwarded as assistant_message text blocks.

Updates InvocationRunner to omit onStdout/onStderr handlers when silent is true for pre/post-agent commands and command-only execution, and bumps versions to 0.14.0 with docs/tests updated to cover the new field and behavior.

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