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/04_solution_strategy.md

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+# Solution Strategy
+
+## Technology decisions
+
+- **Unreal Engine 5.8.4** for rendering, World Partition, physics (Chaos), and the Enhanced Input system. Chosen for its Linux support, open C++ source, and real-time rendering quality.
+
+- **Blender 5.2 LTS** for all 3D modelling, UV work, and collision mesh authoring. Driven headlessly via `bpy` Python scripts, not MCP.
+
+- **QGIS 4.2.3** for geographic data cleanup, coordinate conversion (EPSG:26911), and DEM preparation.
+
+- **Blosm 2.7.28** for OSM building and street blockouts inside Blender (layout data only — not authoritative façade, height, or pavement detail).
+
+- **MPFB 2.0.18** for human base meshes and baked materials (NPCs in `0.2.0+`).
+
+## Top-level decomposition
+
+The system is a single Unreal game module (`GigLine`) with no plugins beyond `EnhancedInput`. Content is organised by domain under `/Game/Hollywood/`:
+
+- `Site/` — terrain, road, sidewalks, kerbs, crossing markings, site materials
+
+- `ElCapitan/` — hero façade mesh and materials
+
+- `Frontage/` — south-side block building meshes
+
+- `North/` — north-side building meshes
+
+- `Input/` — Enhanced Input actions and mapping context
+
+All modelling and geographic processing live outside the game project in `Art/`, `Geo/`, and `Tools/`. The `Game/` directory contains only engine-ready content and C++ source.
+
+## Quality achievement
+
+- **Performance**: dynamic-only lighting (no build step, no static shadow maps), world-space-noise materials (cheap procedural variation), minimal overdraw (simple street-level geometry).
+
+- **Walkability**: complex-as-simple collision on terrain (C++ helper forces the flag on the asset), block-all collision on every site mesh, swept transect QA verifies zero raycast holes.
+
+- **Fidelity**: geographic data verified before modelling (footprints, bounds, DEM); building placement checked against street mesh, never in isolation; reference photography drives façade work.
+
+- **Reproducibility**: pinned toolchain in `Docs/toolchain.md`, named export presets, `Tools/check-lfs.sh` gate, fresh-checkout build procedure in `Docs/build.md`.