Record the bench proof on image 20260829190323 and the warm-loop flow check

CAMPAIGN-LOG: the three flowload t1 runs on the new image (judged rise
11.3, 11.1 and 11.8 C with the tube lit through most of each window, the
laser's share on the line), and Test 3, the flow check from a warm loop
(23.6 to 24.9 C baselines, 0 of 6 wrong, the 14.4 C limit 2.25 C above the
flow band and 3.67 C below the no-flow band).

flow_warm_validate.py takes the warm target and the warm-up budget as
arguments (defaults 28 C, 20 min), and the bench page passes them; the
warm-up still judges on the upstream sensor beside the heater, which is
why this run's baselines stopped near 25 C (BRINGUP item 1).

BRINGUP: item 1's open half is the loop above 25 C; item 22 holds what
remains of the flow check under load.

No catalog consequence: a bench tool's arguments and documentation; no
runtime behavior of the release image changes.

forgetest/forgetest/bench.py

@@ -123,7 +123,9 @@ TOOLS = [
      "desc": "Long run of the real re-check cadence via M8: verdicts, false faults, loop heat accumulation."},
     {"id": "flow-warm", "title": "Coolant warm-baseline validation", "script": "flow_warm_validate.py",
      "safety": "takeover", "where": "board", "ported": True,
-     "args": [_arg("cycles", "int", 3, "cycles per case (flow / no-flow)")],
+     "args": [_arg("cycles", "int", 3, "cycles per case (flow / no-flow)"),
+              _arg("target_c", "float", 28.0, "warm the upstream sensor to this before each check"),
+              _arg("warm_min", "float", 20.0, "warm-up budget per check, minutes")],
      "desc": "Runs the real check (40 percent / 50 s, cut-profile fans) from a heater-warmed baseline, alternating "
              "flow and no-flow; results to the bench data directory. Slow: about 15 minutes per cycle."},
     {"id": "critical-tier", "title": "Coolant critical-tier warm-loop drill", "script": "critical_tier_drill.py",