re(flight): the linear discrepancy is a world-unit vs displayed-speed difference

Screenshotting the HUD speed readout at each throttle step, beside the
position-derived measurement of the same moment:

  RT 0.00   HUD 350 (= CruisingVelocity)   position ~447   ratio 1.28
  RT 0.25   HUD 507                        position ~652   ratio 1.29
  RT 0.75   HUD 963                        position ~1141  ratio 1.19

So (a) the HUD speaks the definition's units — exactly CruisingVelocity at neutral,
963 at three-quarters against the 987 the interpolation predicts — confirming the
throttle law in the game's own numbers without any position sampling; and (b) world
displacement runs ~1.2x the displayed speed. Since settled angular rates need no such
factor, this is a unit difference between the position triple and the velocity
fields, not a clock effect: a reimplementation moving entities at MaximumVelocity in
world coordinates will be ~20% slow.

Also fixes speed_law.find_player: a mission holds more than one *_Player object and
at least one never moves, so the finder now samples each candidate twice and keeps
the one that displaces. Locking onto the static one is what produced a run of exact
zeros while the game was visibly flying.

🟡 The ratio is 1.19-1.29 rather than a clean constant and every sample was taken in
a firefight; pinning it wants a quiet map.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NptfmpjdpNCKEez6d2xvA9

tools/re-capture/throttle_curve.py

@@ -34,7 +34,12 @@ def main():
     for v in (0.0, 0.25, 0.5, 0.75, 1.0):
         pad("trig", "RT", "0.0"); pad("trig", "LT", "0.0")
         pad("trig", axis, str(v))
-        time.sleep(2.5)                       # let the speed converge before sampling
+        time.sleep(6.0)                       # settle: 5 s+ is what the turn-rate fix showed is needed
+        # Screenshot the HUD at the settled speed: its readout is in the
+        # DEFINITION's unit (it shows 350 at neutral = CruisingVelocity), so it is
+        # the ground truth the position-derived number has to be compared against.
+        subprocess.run(["screenshot", f"/sylph-home/re/shots/hud_{axis}_{v}.png"],
+                       capture_output=True)
         seq, t0 = [], time.time()
         while time.time() - t0 < dwell:
             seq.append((round(time.time() - t0, 3), *speed_law.pos_at(w.fd, off)))