bench: let the verdict govern the report, and put the caliber in the table

A pair judged incomparable was still followed by a speedup range on the next
line. A NO_TRITON pair's range says nothing about the switch — nothing reached
the compiler — and a NO_IR_DIFF pair's range is the machine's noise floor for
that operator, which is useful but is not a result. Printing either unlabelled
produces exactly the thing this tooling exists to prevent: a table that looks
like a finding. NO_ROWS and NO_TRITON now print no range; NO_IR_DIFF prints one
and says what it is — how far it sits from zero is the confidence floor for a
single measurement of that operator.

screen.tsv gains the seven caliber columns, read back through
`batch_summary.py --caliber`, so CALIBER_FIELDS stays the single definition and
the screening table does not restate it. Two screen.tsv files taken at
different --level are otherwise indistinguishable side by side, and those
columns are the only thing that would stop the comparison.

README.md

@@ -172,6 +172,20 @@ SWITCH=FLAGTREE_MUSA_RLC_ENHANCE ROUNDS=6 OPS="topk:topk" bash ab_repeat.sh
 同一份 `_ir_fingerprint.sh` 也被 `ab_repeat.sh` 用于第 1 轮后的对比轴有效性检查，
 两处判据不会漂开。
 
+判定还管住报告：`NO_ROWS` 与 `NO_TRITON` 不出 speedup 区间（前者没有可比的测量，
+后者与被测开关无关）；`NO_IR_DIFF` 照出，但明说那是**本机对该算子的噪声底**，不是
+开关的收益——它离零多远，就是该算子单次测量的可信下限。判定刚说完这一对不可比，
+下一行就给个 `+0.3%`，正是这套工具一路在防的"看起来像结论的表"。
+
+`screen.tsv` 末七列是口径（`backend device timer bench_level shape_mode
+tuner_cache direct_repeat`），由 `python batch_summary.py --caliber <run_dir>` 取——
+`CALIBER_FIELDS` 只有那一处定义，筛选表不重列一遍。两份不同 `--level` 的
+`screen.tsv` 放一起比时，这几列是唯一能拦住的东西。
+
+每对有 `CELL_TIMEOUT`（默认 2400 秒）兜底，超时打 `!!! CELL_TIMEOUT` 并按耗时问题
+报告，不混进 dtype 那条解释里。`elapsed_before/after` 也进表：两步流程的全部依据
+就是"一对 0.8 分钟对六轮 13~44 分钟"这个比例，那这一步该记下自己那一半。
+
 ## A/B 对比测试标准流程
 
 ```bash