Add dashboard headless worker mode (CLI flag + worker loop + adapter spawn)

[Kothulhu94]

Motivation

• Provide a dedicated headless mode for the dashboard to run the agent loop via stdin/stdout without launching the interactive TUI.
• Make the Control Room spawn a deterministic worker subprocess instead of relying on the legacy LAUNCHED_BY_DASHBOARD environment handoff.

Description

• Add --dashboard-worker (alias --headless-worker) to src/cli/args_parser.js and document it in the help text.
• Implement a lightweight dashboard worker loop in bin/smallcode.js (runDashboardWorker) that accepts plain lines or JSON-lines, extracts a command/prompt, calls runAgentLoop(input, config), captures output, and emits lifecycle markers such as [HARNESS] ready, [user] ..., [assistant] ..., [IPC] Run Complete, and [IPC] Error: ... to stdout.
• Hook the worker into startup before the normal TUI path by checking flags.dashboardWorker in main() and suppressing some human-facing output in worker mode.
• Update src/controlroom/harness_adapter.js:startTUI() to spawn node bin/smallcode.js --dashboard-worker and remove the LAUNCHED_BY_DASHBOARD env dependency.
• Add focused unit tests test/cli_args_parser.test.js and test/controlroom_harness_adapter.test.js to validate argument parsing and spawn behavior.

Testing

• Ran node --check bin/smallcode.js to ensure file parses without syntax errors, and it succeeded.
• Ran unit tests with node --test test/cli_args_parser.test.js test/controlroom_harness_adapter.test.js, and both tests passed.
• Ran node test/e2e_offline.js which failed in this environment due to a missing installed dependency (chalk) unrelated to the new worker logic; the failure prevented the full offline smoke checks but does not affect the new worker/unit tests.

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[chatgpt-codex-connector]

Preserve raw JSON prompts without envelope fields

When the dashboard sends a plain prompt that happens to be a JSON object, this branch parses it as a worker envelope and replaces it with only command/input/prompt/text. For inputs like {"scripts":{"test":"node --test"}} none of those fields exist, so this returns an empty string and runOne silently ignores the user request; objects containing a text or command property are also unintentionally truncated. Since sendCommand() writes raw user text, treat parsed JSON as an envelope only when one of the supported fields is actually present, otherwise fall back to the original line.

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