re: making turrets targets does not save the escort — the effect is inside the noise

The Stage-02 outcome write-up ended by naming "turrets near the asset must
become targets" as the fix worth ~50% of the escort damage. That was an
inference from a co-presence attribution, not a measurement. Run it and it
does not hold.

Also corrects the run labelling: pilot.py gained the SYLPH_KILL_TURRETS gate
two minutes before mission02 started, so mission02 was already a treatment run,
not a second baseline. Only mission01 (0 of 3968 pilot frames targeting a
turret) is the baseline.

At a common t=428s: baseline 46.9% escort hull, treatment 44.5% and 53.0%. The
two runs of the same arm differ by more than either differs from the baseline,
and the escort still reaches zero at t~590-670s in all three. So the
transferable finding is the power limit: one 430s flight cannot resolve an
effect below ~9 percentage points, and every single-run pilot conclusion,
including this one's, is inside it.

What does reproduce: the assault is scripted (onset 166/167/166s), and the
e007/e010 damage split is 50/50 in all three arms including the one that never
fires at a turret -- so that attribution measures the wave script, not us.

Also records that the viewer's include_external hypothesis in BACKLOG is dead
(it defaults true and is threaded through unchanged).

docs/re/BACKLOG.md

@@ -58,3 +58,26 @@ class cannot hide behind `e106` passing.
 handedness, node-instance recursion) is not re-breaking a correct assembly — compare
 the viewer's placement against `assemble_ship`'s output directly before blaming the
 format layer.
+
+---
+
+## Viewer: `include_external` is already on — that hypothesis is dead
+
+**Checked 2026-08-11.** The item above names "first that it passes
+`include_external = true` (`iso_loader.rs:4012`)" as the cheap first step. It
+does: `ShipBrowser::show_external` defaults to `true`
+(`iso_loader.rs:643`), the checkbox reads it (`ui.rs:1593`) and it is threaded
+through `RequestShipRender` → `build_ship_model` → `assemble_ship` unchanged
+(`ui.rs:1689`, `iso_loader.rs:4012`). So a ship rendered by the viewer is the
+full external assembly, not the bare hull.
+
+The viewer also does not have a transform stack of its own to blame: it bakes
+`ScenePart::apply` straight into the vertices and rotates normals by the same
+`p.m` (`iso_loader.rs:4030-4062`), so its placement is `assemble_ship`'s output
+by construction. What remains unexcluded, in order of cheapness: the mirror
+handling (`det < 0` reverses triangle winding only — a reflected part keeps its
+reflected geometry), `Xbg7Model::models_named` resolving the wrong sub-model when
+a resource name repeats, and the exhaust cones. **Next step is a visual**: the
+diagnosis has run out of things it can settle by reading, so the viewer needs to
+be run against a known-good class (`e106`) and its render compared with
+`ship_render`'s.