qa: make the demo walkable — terrain collision root cause, spawn, scripted QA

The reported fall-through was a misdiagnosis: the player never fell. The
imported Terrain_DEM had only a bounding-box simple collision proxy, so a
downward trace anywhere in the block hit the terrain at Z 819 (the mesh
bbox max) and the street sat under an invisible 8 m lid. Standing on that
box looked plausible, which is why it read as working.

- add UGigLineAssetTools (C++): force CTF_UseComplexAsSimple on a static
  mesh. UE 5.8 dropped bUseComplexAsSimpleCollision and Python cannot set
  the flag; the builder also saves the asset, since the flag lives there
  and a map-only save silently reverts it.
- spawn (-13336, -1150, 600): inside the carved corridor (the cut is a
  10.7 m half-width around the road centreline), lands on the road at 456.
- fix ResetToStart returning to the mid-air PlayerStart captured in
  BeginPlay: StartLocation is now captured on the first grounded frame.
- HighResShot 1280x720 instead of "1280 720", which is a multiplier.
- add -qaselftest: scripted walk/reset/pause on a core ticker plus a
  swept ground transect. Results: walk 746 cm/2 s with Z steady, reset
  0 cm from spawn, pause/unpause 1/0, transect 84 samples 0 holes.
- rebase onto main, keeping the frontage materials and placement fixes.

Game/GigLine/Config/DefaultEngine.ini

@@ -1,5 +1,11 @@
 [/Script/EngineSettings.GameMapsSettings]
 GlobalDefaultGameMode="/Script/GigLine.GigLineGameModeBase"
+; The runnable map is the walkable demo, so a plain launch opens it (not the
+; engine template nor the review staging scene).
+GameDefaultMap=/Game/Hollywood/DemoMap
+EditorStartupMap=/Game/Hollywood/DemoMap
+ServerDefaultMap=/Game/Hollywood/DemoMap
+TransitionMap=/Game/Hollywood/DemoMap
 
 [/Script/Engine.RendererSettings]
 ; Dynamic-only lighting. With static lighting allowed, the stationary sun and

Game/GigLine/Config/DefaultGame.ini

@@ -7,9 +7,14 @@ CopyrightNotice=
 BuildConfiguration=PPBC_Development
 FullRebuild=False
 UsePakFile=True
+; Runtime-loaded content must ship even when nothing statically references it.
+; The Enhanced Input assets are only soft-loaded by AGigLineCharacter at
+; BeginPlay; without this the cooker prunes them from the pak (observed: the
+; cook ReferencedSet had zero /Game/Input entries, so inputs were all nil and
+; no keys worked). Always cook the demo map + input. Keep both maps listed so
+; EditorStartupMap/GameDefaultMap selection stays flexible.
++DirectoriesToAlwaysCook=/Game/Input
++DirectoriesToAlwaysCook=/Game/Hollywood
++DirectoriesToAlwaysCook=/Game/Test
+
 
-[/Script/EngineSettings.GameMapsSettings]
-; Temporary default while the demo map is being built; GameMapsSettings in
-; DefaultEngine.ini still names the game mode only.
-GameDefaultMap=/Game/Test/ReviewMap
-EditorStartupMap=/Game/Test/ReviewMap