docs: update AGENTS.md to reflect current project structure

- Update source layout with scenes/ directory and static libraries
- Add static library documentation (cbt_opengl, cbt_scene, scenes_cube)
- Remove stale references to nerv project
- Update run command for Windows

AGENTS.md

@@ -15,21 +15,29 @@
   ```sh
   cmake -S . -B build -GNinja
   ninja -C build
-  ./build/cuber
+  .\build\cuber.exe
   ```
 
 ### Dependencies
 
 Dependencies are managed via custom `Find*.cmake` scripts in `deps/`.
 These scripts use `FetchContent` under the hood to download and build
-libraries automatically. They are shared with the `nerv` project.
+libraries automatically.
 
 To add a new dependency:
 
-1. Copy the corresponding `Find<name>.cmake` from `nerv/deps/`
+1. Add the corresponding `Find<name>.cmake` to `deps/`
 2. Add `find_package(<name> REQUIRED)` to `CMakeLists.txt`
 3. Link with `<name>::<name>` in `target_link_libraries()`
 
+### Static Libraries
+
+The project is split into static libraries:
+
+- **`cbt_opengl`** — OpenGL abstraction (context, buffer, texture, vao, shader, descriptor)
+- **`cbt_scene`** — Base scene class
+- **`scenes_cube`** — Cube scene implementation
+
 ### CMake Module Path
 
 `deps/` is added to `CMAKE_MODULE_PATH` so `find_package()` resolves
@@ -91,7 +99,9 @@ Example:
 cuber/
   CMakeLists.txt      # Build configuration
   cuber.cpp           # Entry point
-  cbt/                # Project namespace
+  cbt/                # Project namespace (utilities)
+    scene.hpp         # Base scene class
+    scene.cpp         # Scene implementation
     opengl/           # OpenGL abstraction layer
       context.hpp     # OpenGL context RAII wrapper
       context.cpp     # Context implementation
@@ -101,13 +111,19 @@ cuber/
       texture.cpp     # Texture implementation
       descriptor.hpp  # Descriptor set (Vulkan-style binding)
       descriptor.cpp  # Descriptor implementation
+      shader.hpp      # Shader program
+      shader.cpp      # Shader implementation
+      vao.hpp         # Vertex array object
+      vao.cpp         # VAO implementation
+  scenes/             # Application scenes
+    cube.hpp          # Spinning cube scene
+    cube.cpp          # Cube scene implementation
   deps/               # Custom Find*.cmake scripts
     Findfmt.cmake     # fmt library
 ```
 
 ## Platform Support
 
-The `nerv` project supports Windows, Linux, Emscripten, and Android via
-`Platform.cmake` and `Flags.cmake`. These can be added to `cuber/deps/`
-when cross-platform support is needed.
+The project supports Windows, Linux, Emscripten, and Android via
+`Platform.cmake` and `Flags.cmake` in `deps/`.