Add a 'State' column to the 'agents resource list' rich table output that
shows the current lifecycle state for devcontainer-instance and
container-instance resources. For newly-discovered devcontainers the state
displays as 'detected (not built)'; running, stopped, and failed states are
also shown.
Changes:
- Add _get_lifecycle_state_str() helper that queries get_lifecycle_tracker()
for container resource types and returns a human-readable state string
- Add 'State' column to the rich table in resource_list()
- Show warning banner '⚠ Devcontainer detected at ...' for resources in
the detected state, matching the spec output for agents resource add
- Update _resource_dict() to include 'lifecycle_state' field in JSON/YAML
output (null for non-container resources)
- Add BDD feature file and step definitions covering all lifecycle states,
warning banner behaviour, and JSON output
ISSUES CLOSED: #2596
freemo