Ability to run agent for a given task in detached mode

[nezhar]

Summary

Add support to run an agent for a given task in detached mode, where the process runs in the background, returns immediately with a task ID, and logs/results are stored locally.

Expected Behavior

• User can run an agent with a --detach or --detached option.
• CLI returns immediately with a task/run ID.
• The agent execution continues in the background.
• All logs and results are stored in local SQLite DB and are associated with the task ID.
• CLI allows retrieving task results and logs by ID after completion, e.g., via run logs <id> or run attach <id>.

Motivation

Some tasks may be long-running, and users may wish to start these asynchronously or in the background, rather than blocking their current session. Storing logs and results for retrieval improves workflow efficiency.

Acceptance Criteria

• Support for running agent tasks in detached/background mode.
• Task/run ID is returned to the user immediately upon starting.
• Results and logs are persisted and accessible via the CLI.
• Documentation and help text updated for detached mode usage.

Additional Context

• Ensure that running in detached mode does not conflict with existing synchronous task running or logging behavior.