feat(hero): one-command iteration loop, first judged pass, comparison plates

Tools/hero_iterate.sh runs the whole chain - chmod the Blender files, build, import, render, judge, plate -
and fails loudly at each step with its log under /tmp/gigline. Tools/hero_compare.py builds the side-by-side
plate (reference | rendered, one height, labelled); two are committed for review.

This pass: the stone is warmer in Blender (0.66/0.60/0.48 against the near-white blockout) and the banners are
1.35 x 6.2 m hung from 7.2 m, matching the reference proportion instead of the 1.55 x 5.4 that sat too low and
too fat.

Iteration 1 judge verdict, confidence 0.9: lacks warm sandstone, lacks fluted column detail, banners wrong,
no doorways, no inscription or medallions. Checked against the plate, two of those are wrong (120 flute
strips exist and cast shadows; three 1.2 m deep doorways with steps exist and read black) and three are real.
The split is recorded in TODO.md with the next action for each - the important one being that the stone colour
must change in the UE material (ue_hero_facade_import.py), not in the Blender material, which the render does
not use.

TODO.md

@@ -169,6 +169,24 @@ Done in this pass:
 
 Still missing, from the same references: warm sandstone instead of the flat pale stone, lattice grilles in the window bays, the carved inscription on the motto band, and the two medallions are not reading at distance.
 
+### The iteration loop
+
+`bash Tools/hero_iterate.sh` runs the whole chain in one command: chmod the Blender files, build the facade, import it, render the capture set, judge the shot with the vision model, and write a comparison plate at `Screenshots/review/hero-compare-front.png`. Each step fails loudly and logs to `/tmp/gigline/`.
+
+Iteration 1 verdict (judge, confidence 0.9):
+
+> "The scene lacks the warm yellow-grey sandstone texture and the detailed fluted Ionic columns. Additionally, the red banners do not match the expected design, and there are no visible entrance doorways or decorative elements like the inscription band or medallions."
+
+Measured against the plate, that splits into:
+
+| Finding | Reality | Next action |
+| --- | --- | --- |
+| not warm sandstone | true - the UE material `M_FacadeStone` is still near-white (0.62-0.76 grey) | warm the UE material spec in `Tools/ue_hero_facade_import.py`, not the Blender one |
+| fluting missing | false - 120 flute strips exist and cast shadows; they are lost at 45 m | not a modelling problem; check the review camera distance |
+| banners wrong | partly - proportions are now 1.35 x 6.2 m and hang correctly, the lettering is absent | needs a texture, not geometry |
+| no doorways | false - three 1.2 m deep recesses with steps; they read dark because the reveal is glass-black | lighten the reveal material |
+| no inscription/medallions | true - the band and two medallions exist but are flat and untextured | texture the motto band |
+
 ### Tasks
 
 - [x] Confirm the hero captures frame `Hero_Facade` - **done**: the cameras are aimed at (-13336, 1307), the hero actor is there, and the frontage is at the origin.