merge: bring main (v0.1.6) into anim-body-0.2.0

Conflicts resolved by union, not by picking a side:

- AGENTS.md keeps the stronger visual-review rule (README updated with every visual
  change; a stale section is a defect).
- render_screenshots.sh keeps the absolute engine path from main and adds
  -thirdperson from this branch - both were needed and neither alone worked.
- Screenshots/README.md now lists six shots, retail and third-person both embedded;
  the known-issues tables merged, with the animation defect and unproven camera
  collision added to main's rows.
- visual_targets.json carries both expectations.
- Architecture docs: ADR-8 (realistic buildings) and ADR-9 (third-person body) both
  present and in numeric order; ADR-8 was mis-placed before the Quality Requirements
  heading in the combined document by an earlier edit, now fixed.
- Binary conflicts resolved to main's content, since the retail trim only exists
  there.

Checks: 82 tool tests, prettier clean, six embeds resolve.

Tools/render_screenshots.sh

@@ -39,9 +39,9 @@ run_cmdlet ue_build_review_map.py "5/6 stage the demo shot cameras"
 tail -3 /tmp/ue-review-map-result.txt 2>/dev/null || true
 
 echo "== 6/6 capture the demo map =="
-# Absolute engine path: this step runs from the repo, not from $ENGINE, and a bare
-# ./Engine/... failed with "No such file or directory" while every commandlet above
-# succeeded through run_cmdlet's cd. -thirdperson so the review shows the body.
+# The engine path is absolute: this step runs from the repo, not from $ENGINE, and a
+# bare ./Engine/... failed with "No such file or directory" while every commandlet
+# above succeeded through run_cmdlet's cd.
 "$ENGINE/Engine/Binaries/Linux/UnrealEditor-Cmd" "$PROJ" /Game/Hollywood/DemoMap \
   -game -windowed -ResX=1920 -ResY=1080 -nopause -nosplash -thirdperson -stdout