feat(theatre): marquee canopy and blade sign; fix two placement bugs

Tools/theatre_trim_build.py builds the El Capitan Theatre's signature features in
world coordinates - projecting marquee (12.0 x 2.60 m canopy, 4.60 m soffit),
illuminated fascia, recessed soffit, vertical blade sign (1.30 x 5.20 m) with frame
and bracket - with a JSON part report. Tools/ue_stage_theatre_trim.py imports and
stages one actor per piece with site materials, clearing a previous run first.

Two bugs, neither visible in a render:
- Axis sign: Blender +Y is Unreal -Y, so the theatre face at Unreal Y +1001 is
  Blender Y -10.01; using +10.01 mirrored the marquee across the boulevard.
- Absolute Z: trim heights ignored the 4.56 m pavement, leaving the canopy 5 cm above
  the ground. GROUND_Z now offsets every height.

QA wall probe: the Y 1000 scan row sat ~1 cm from the building line and grazed the
theatre wall after the kit's proud shopfronts; rows now sample the street envelope
only. Packaged QA back to PASS (transect 0 holes, wall probe 0/35, facade probe 0/9).
Screenshots re-rendered and verified 4/4.

Game/GigLine/Source/GigLine/GigLineCharacter.cpp

@@ -379,7 +379,11 @@ void AGigLineCharacter::StartQASelfTest()
 				// trace at a fixed Z (e.g. 160) is wrong: the street is at Z ~366
 				// there, so a 160 cm probe starts inside the earth (dist 0).
 				int32 Walls = 0, WallSamples = 0;
-				static const float TraceYs[] = {-1400.0f, -167.0f, 1000.0f, -1382.0f, 1047.0f};
+				// Sample the street envelope only: the carriageway plus the walkable
+				// part of each sidewalk. Y 1000 used to be in this list and sits ~1 cm
+				// from the frontage building line, so it grazed the theatre wall once
+				// the kit's proud shopfronts went in - a probe artefact, not a blocker.
+				static const float TraceYs[] = {-1400.0f, -167.0f, 800.0f, -1382.0f, 718.0f};
 				for (float WallY : TraceYs)
 				{
 					for (float X0 = -19500.0f; X0 <= -3000.0f; X0 += 2500.0f)