Add documentation folder READMEs and visual previews

Create an index README in docs/ and every tracked docs subfolder, with relative
image galleries for Blender previews, screen designs, screenshots and concepts.
Generated realism-run READMEs were also created on disk but remain gitignored.
Validate all Markdown/image links.

docs/adr/README.md

@@ -0,0 +1,20 @@
+# Architecture Decision Records
+
+Each ADR records the context, decision, consequences and alternatives for a durable architecture choice.
+
+## Decisions
+
+- [0001-venue-driven-simulation-architecture](0001-venue-driven-simulation-architecture.md)
+- [0002-de-escalation-first-escalation-model](0002-de-escalation-first-escalation-model.md)
+- [0003-explicit-access-verification-system](0003-explicit-access-verification-system.md)
+- [0004-local-single-player-first](0004-local-single-player-first.md)
+- [0005-event-based-incident-recording](0005-event-based-incident-recording.md)
+- [0006-godot-4-gdscript](0006-godot-4-gdscript.md)
+- [0007-locomotion-and-input-layers](0007-locomotion-and-input-layers.md)
+- [0008-cone-focus-and-head-ring](0008-cone-focus-and-head-ring.md)
+- [0009-radial-action-menu](0009-radial-action-menu.md)
+- [0010-procedural-npc-presentation](0010-procedural-npc-presentation.md)
+- [0011-aim-free-selection-and-precision-walk](0011-aim-free-selection-and-precision-walk.md)
+- [0012-surface-materials-and-generated-props](0012-surface-materials-and-generated-props.md)
+- [0013-blender-authored-npc-characters](0013-blender-authored-npc-characters.md)
+- [0014-runtime-image-root](0014-runtime-image-root.md)