Flow-detection experimental record and bench tooling

Adds the design matrix and its supporting tools, and records in BRINGUP
what the 60-run matrix overturned: sub-40-percent duty mimics flow
(three of five dead-pump trials looked healthier than a working pump),
the operating point and threshold now rest on 25 pooled observations,
periodic re-checks are thermally free with the fans running, and the
settle gate closes a bench-proven miss. Also records what is NOT yet
validated - warm-loop baselines and behaviour under laser heating - as
first-light commissioning items.

scripts/bench/flow_warm_results.json

@@ -0,0 +1,32 @@
+[
+ {
+  "flow": true,
+  "base_up": 20.90741361785507,
+  "base_down": 21.837331209719537,
+  "down_rise": 11.480714695811116,
+  "up_rise": 2.254025184475836,
+  "peak_down": 34.43702357179029,
+  "t": 49.15,
+  "cycle": 0
+ },
+ {
+  "flow": false,
+  "base_up": 21.371932016053336,
+  "base_down": 21.914988917022924,
+  "down_rise": 12.176080123337613,
+  "up_rise": 1.5552007482007184,
+  "peak_down": 34.09106904036054,
+  "t": 49.17,
+  "cycle": 0
+ },
+ {
+  "flow": true,
+  "base_up": 21.06216007856807,
+  "base_down": 21.75970016295645,
+  "down_rise": 11.302272149723365,
+  "up_rise": 2.6471638813487743,
+  "peak_down": 34.1774170676689,
+  "t": 49.16,
+  "cycle": 1
+ }
+]