Refactor documentation structure and add new specifications

- Updated MSH documentation to reflect changes in material, wear, and texture specifications.
- Introduced new `render.md` file detailing the render pipeline process.
- Removed outdated sections from `runtime-pipeline.md` and redirected to `render.md`.
- Added detailed specifications for `Texm` texture format and `WEAR` wear table.
- Updated navigation in `mkdocs.yml` to align with new documentation structure.

crates/render-core/README.md

@@ -0,0 +1,14 @@
+# render-core
+
+CPU-подготовка draw-данных для моделей `MSH`.
+
+Покрывает:
+
+- обход `node -> slot -> batch`;
+- раскрытие индексов в triangle-list (`Vec<[f32;3]>`);
+- расчёт bounds по вершинам.
+
+Тесты:
+
+- построение рендер-сеток на реальных `.msh` из `testdata`;
+- unit-test bounds.