feat: report a per-operator speedup range across two runs

The speedup column in a result table compares gems against torch, not one build
against another, so an A/B needs the two runs paired by shape. batch_summary
gains an --ab mode that indexes both run.logs by operator, dtype and size
detail, computes before/after per pair, and prints the per-shape rows plus the
range. Only rows that succeeded on both sides with a positive latency count, so
an incomplete pairing cannot masquerade as a complete range. When either side
carries a BENCHMARK_DIRECT_NO_CUDAGRAPH marker the range is annotated, because
a fallback row was timed under a different regime than a captured one.

ab_rlc_test.sh drives the pairing for the FlagTree RemoveLayoutConversions
switch the way ab_fold_test.sh does for the FlagGems one: per operator, run with
the enhancement off while recording autotune configs, then replay those configs
with it on, so the two sides differ by that switch alone. Each operator
therefore leaves exactly two run.log files, and the summary of each pair is
printed as it completes.

Checked on an S5000 against gelu_backward over five shapes: both sides captured
with no fallback, five rows paired, range -0.43% to +0.09%.

ab_rlc_test.sh

@@ -0,0 +1,68 @@
+#!/bin/bash
+# A/B 对比：FlagTree RemoveLayoutConversions 增强关 vs 开，逐算子两轮。
+#
+# 口径：每个算子先跑关（record autotune config），再用 REPLAY_FROM 回放同一套
+# config 跑开，两侧只差 FLAGTREE_<VENDOR>_RLC_ENHANCE 这一个开关。产物沿用
+# run_pytest.sh 的目录结构，所以每个算子恰好留下两份 run.log：
+#
+#   runs/<op>_<时间戳>/run.log   关（before）
+#   runs/<op>_<时间戳>/run.log   开（after）
+#
+# 跑完用 batch_summary.py --ab <before> <after> 得到该算子的 speedup 区间。
+#
+# 用法：
+#   OPS="softmax gelu_backward" bash ab_rlc_test.sh
+#   OPS="sort:perf_sort topk" bash ab_rlc_test.sh     # 冒号分隔 OP:OP_FILE
+#
+# 注意：RLC 开关名带厂商前缀，用 VENDOR 指定（默认 MUSA）。套用前先确认开关有效：
+# grep 该开关名于 FlagTree 源码应有命中，否则两侧跑的是同一份代码。
+set -uo pipefail
+
+cd "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+VENDOR="${VENDOR:-MUSA}"
+ENHANCE_VAR="FLAGTREE_${VENDOR}_RLC_ENHANCE"
+
+# 空格分隔的算子表。元素为 OP 或 OP:OP_FILE（省略时 OP_FILE=OP）。
+OPS="${OPS:-softmax}"
+
+if [[ -t 1 && -z "${NO_COLOR:-}" ]]; then
+  export FLAGGEMS_PERF_COLOR=always
+fi
+
+LOG="runs/ab_rlc_$(date +%Y%m%d-%H%M%S).log"
+mkdir -p runs
+
+{
+  echo ">>> vendor=$VENDOR  switch=$ENHANCE_VAR  ops=$OPS"
+  for entry in $OPS; do
+    op="${entry%%:*}"
+    op_file="${entry#*:}"
+    [[ "$op_file" == "$entry" ]] && op_file="$op"
+
+    echo "########## $op | $ENHANCE_VAR=0 before (record) ##########"
+    if ! OP="$op" OP_FILE="$op_file" env "$ENHANCE_VAR=0" bash run_pytest.sh; then
+      echo "!!! FAILED before: $op"
+      continue
+    fi
+    BEFORE=$(ls -dt "runs/${op}_"* | head -1)
+
+    echo "########## $op | $ENHANCE_VAR=1 after (replay $BEFORE) ##########"
+    if ! OP="$op" OP_FILE="$op_file" REPLAY_FROM="$BEFORE" env "$ENHANCE_VAR=1" bash run_pytest.sh; then
+      echo "!!! FAILED after: $op"
+      continue
+    fi
+    AFTER=$(ls -dt "runs/${op}_"* | head -1)
+
+    echo "########## $op | summary ##########"
+    python batch_summary.py --ab "$BEFORE/run.log" "$AFTER/run.log" --label "$op" \
+      || echo "!!! summary failed: $op"
+  done
+  echo "########## ALL DONE ##########"
+} 2>&1 | tee "$LOG"
+
+# 去掉 ANSI 转义以便 grep/diff（终端输出保留颜色）
+sed -i -E $'s/\x1b\\[[0-9;]*[A-Za-z]//g' "$LOG"
+
+echo ">>> 总 log: $(pwd)/$LOG"
+echo ">>> 每算子两份 run.log 在 runs/<op>_<时间戳>/ 下，按时间先后即 before / after"