tui 4/8: reorder + conflict escape hatch (resolve/undo, suspend/resume)

[freshtonic]

Parent

#1 — git queue tui — interactive queue/history editor (TUI)

What to build

Reorder a commit within the queue line, and the shared conflict escape hatch that every rewriting operation reuses.

• Reorder a commit up or down; the engine performs the rebase immediately; the commit's Stable-Commit-Id is preserved. Reordering a commit across a boundary reassigns it to the branch whose run it lands in.
• Conflict handling: when an operation conflicts, prompt "<operation> produced conflicts. [R]esolve or [U]ndo?".
  • Resolve suspends the TUI to the shell, leaving the user in the standard mid-rebase state (consistent with sync's resume-by-re-run); re-entering git queue tui resumes the session.
  • Undo backs the operation out via the undo stack — nothing left applied.
• No predictive pre-conflict trial: a conflicting move is simply attempted.

Acceptance criteria

• Reorder moves a commit up/down and rebases immediately, preserving its Stable-Commit-Id.
• A reorder across a boundary reassigns the commit to the correct branch.
• A conflicting reorder shows the resolve/undo prompt.
• Choosing resolve suspends to the shell in the mid-rebase state; re-entry resumes cleanly.
• Choosing undo reverts the operation with nothing applied.
• Engine integration tests cover a clean reorder, a cross-boundary reorder, and a conflicting reorder taken down both the resolve and the undo paths.

Blocked by

• tui 3/8: boundary edits, undo/redo, quit-guard & exit #4 (ticket 3 — boundary edits, undo/redo & exit).