docs: convert all architecture .adoc sections to markdown, prettier-format all .md

- Converted 13 individual .adoc section files to .md via
  asciidoctor→docbook5→pandoc(gfm) + post-processing, placed alongside
  the .adoc sources in Docs/Architecture/
- Rebuilt architecture.md from the individual section .md files
- Ran prettier --write on all .md in the repo (23 files changed):
  normalised table column alignment, trailing whitespace, line breaks
- Added .agents/ to .prettierignore (vendored third-party content)
- All .md now passes prettier --check

Docs/Architecture/03_context_and_scope.md

@@ -0,0 +1,22 @@
+# Context and Scope
+
+## Business Context
+
+The system is a self-contained single-player game. It has no server backend, no multiplayer, and no live service dependencies. Its communication partners are:
+
+| Partner | Inbound | Outbound |
+| --- | --- | --- |
+| Player (keyboard/mouse) | WASD, mouse, R (reset), Escape (pause), Space (jump) | Rendered 3D scene + HUD |
+| OSM data | Extracted building footprints, street geometry, elevation | Attribution string at runtime |
+| Filesystem | Engine content (`.uasset`, `.umap`), Blender sources (`.blend`), DEM GeoTIFF | Saved maps, screenshots, packaged build |
+
+## Technical Context
+
+| Channel | Protocol / Format | Purpose |
+| --- | --- | --- |
+| Keyboard + mouse | Enhanced Input (IA\_\*, IMC_Default) | First-person movement, look, jump, reset, pause |
+| Vulkan RHI | GPU rendering | Scene display at 60 FPS / 1440p |
+| FBX | Autodesk FBX (binary) | Blender→Unreal mesh and skeleton transfer |
+| GeoTIFF | 3DEP 1 m DEM | Terrain heightfield source |
+| OSM XML | Overpass API extract | Building footprint and street layout source |
+| Git / LFS | HTTPS to Gitea remote | Source control, binary asset storage |