Implements the three Rich panels required by specification.md §"agents session export"
(lines 1987–2115) that were missing from the export_session() command.
Changes:
- Add _render_export_panels() helper that renders three spec-required panels:
* "Session Export" panel: session ID, output path, message count, file size, format
* "Contents" panel: messages, plan references, metadata keys, actor config, schema version
* "Integrity" panel: checksum (sha256:xxxx...xxxx), encrypted flag
- Fix success message from "Session exported to {output}" to "Export completed"
- Fix stdout export path to also render Rich panels (previously only printed raw JSON)
- Keep --format and --force options (useful extensions, do not break spec compliance)
- Update Behave scenarios in features/session_cli.feature to verify panel rendering
- Update Robot Framework helper and test file with new export panel assertions
ISSUES CLOSED: #3424
freemo
brent.edwards