Cherry-pick from d6acf1a with manual merge resolution.
Keep onboarding edits in draft state until users choose Done or Save and
Exit, so backing out or discarding the wizard no longer persists partial
changes.
Co-Authored-By: Jason Zhao <144443939+JasonZhaoWW@users.noreply.github.com>
PR #881 (commit 755e424) fixed the race condition between normal consolidation
and /new consolidation, but did so by making /new wait for consolidation to
complete before returning. This hurts user experience - /new should be instant.
This PR restores the original immediate-return behavior while keeping safety:
1. **Immediate return**: Session clears and user sees "New session started" right away
2. **Background archival**: Consolidation runs in background via asyncio.create_task
3. **Serialized consolidation**: Uses the same lock as normal consolidation via
`memory_consolidator.get_lock()` to prevent concurrent writes
If consolidation fails after session clear, archived messages may be lost.
This is acceptable because:
- User already sees the new session and can continue working
- Failure is logged for debugging
- The alternative (blocking /new on every call) hurts UX for all users
On Windows, sys.argv[0] may be just "nanobot" without full path when
running from PATH. os.execv() doesn't search PATH, causing restart to
fail with "No such file or directory".
Fix by using `python -m nanobot` instead of relying on sys.argv[0].
Fixes#1937
chengyongruandXubin Ren
