Support OSC 7501 program status in the interactive CLI #5112

Describe the feature or problem you'd like to solve

Report agent state to supporting terminals using OSC 7501.

Proposed solution

Please emit OSC 7501 Program Status Protocol reports from the interactive TUI: working, blocked (permission/question/auth), done/error, and idle, with a stable app name. Keep escape sequences out of JSON, ACP, and other machine-readable output.

When several agents run in separate terminal tabs, supporting terminals can show which are working, need input, or have finished without parsing screen text.

Example prompts or workflows

• See that a background agent is still working.
• Identify a tab waiting for approval or an answer.
• Notice a completed or failed turn without opening every tab.

Additional context

Prior art: Crush and Codex have merged support.