fix(rectification): do not hold delivery on exhausted or closed-ceiling paths (BUG-688)

Style questions still precede a converging range card when a renderable
followup exists. Exhausted, closed-ceiling, and holdout-unavailable exits
deliver immediately. Hold at most once per Case. Restore the single-gate
exit assertion and stop treating the tie-break ack as an exit carrier.

frontend/DESIGN.md

@@ -234,7 +234,7 @@ The birth-time rectification session is the consultation transcript plus a house
 | `question-gap`, delivered | no current question, or the current question is a dead choice card, and the session already delivered a range (`completed_with_range` / `provisional_range` / adopt outcomes, or `tied_first`); range card or range line plus an exit note. Never “没有拿到下一个问题。” | enabled |
 | `verified_idle` | one closing line `postAdoptVerifyDone` under the still-visible range card (same assistant column); no spinner, no reload | enabled |
 | `choice-pending` | the answered card (`data-selected` fill, a top row “正在记录…”) and the same live row from “正在记录本次选择…” through the follow-up turn | enabled (typing queues), stop visible |
-| `candidates` | one range-delivery card titled “目前范围 …（对照了 N 件经历）”, a caption under the title that only names still-open lines (or “能问的都问完了”); optional “再答两道参考题微调排序” only when unused D9/D10 remain; if those were already asked and the top two are still within one point, a line “这两分钟按现有信息分不开，参考题已经用过。”; then up to three compare columns (highest posterior first; “更像这个” adopts); a closed “查看验证报告” fold. Unused style questions are asked before this card appears, whether or not the top two are tied. | enabled |
+| `candidates` | one range-delivery card titled “目前范围 …（对照了 N 件经历）”, a caption under the title that only names still-open lines (or “能问的都问完了”); optional “再答两道参考题微调排序” only when unused D9/D10 remain; if those were already asked and the top two are still within one point, a line “这两分钟按现有信息分不开，参考题已经用过。”; then up to three compare columns (highest posterior first; “更像这个” adopts); a closed “查看验证报告” fold. On a normal convergence, unused style questions are asked before this card. Exhausted and closed-ceiling exits still deliver the card if a style question cannot be rendered. | enabled |
 | `adopting` | “正在采用 HH:MM…” through the follow-up turn | enabled (typing queues), stop visible |
 | `confirmed` | “已确认校正时间：HH:MM” | enabled |
 | `readonly` | “该校正已结束，只能查看历史。” and “再次校正” | disabled |