Surface and recover from rebase or push conflicts

[Adjanour]

Summary

Enhance the end-of-session workflow so rebase and push conflicts are detected, paused cleanly, and resumable once the user resolves issues.

Motivation

• README.md Phase 3 roadmap highlights conflict handling as required polish.
• docs/MVP1-SUMMARY.md lists conflict detection and guidance as part of the next milestone.

Scope

• Detect conflicts during git rebase or git push inside sess end.
• Pause the workflow with clear instructions that follow docs/cli_design_guide.md.
• Persist intermediate state so users can resume after manual fixes.
• Provide a resume path that continues PR creation once conflicts are resolved.
• Add safeguards to prevent partial session termination.

Out of Scope

• Automatic conflict resolution.
• Support for parallel sessions.

Acceptance Criteria

• When conflicts arise, the CLI pauses, prints actionable guidance, and keeps the session state consistent.
• After manual conflict resolution, rerunning the end workflow resumes without redundant steps.
• QA notes document conflict, abort, and resume scenarios.

References

• README.md (Phase 3: Conflict Handling)
• docs/technical-spec.md
• docs/MVP1-SUMMARY.md
• docs/cli_design_guide.md

[Adjanour]

With sess end now implemented, this is the remaining Phase 3 item.\n\nCurrent local/docs status:\n- sess end now commits dirty work, rebases onto the tracked base branch, pushes, creates or reuses a PR, switches back to base, and persists PR metadata\n- README and roadmap docs were updated to mark sess end delivered\n- the next gap is resumable conflict/interrupted-workflow handling so rebase/push failures can be recovered without redundant steps\n\nKeeping this issue open as the next follow-up after the v0.3.0 session-end release work.