[Lay-quq]

Fixes #2717

GltfLoader.readCameras() looked up the perspective camera's aspect ratio under the key "aspectRation", but the glTF 2.0 spec names it aspectRatio. The lookup never matched, so every perspective camera loaded from a glTF file got an aspect ratio of 1 regardless of what the file said.

This changes the key to aspectRatio. The fallback when the property is missing is still 1, as before; using the viewport's aspect ratio in that case (as the spec suggests) is a separate change and not part of this PR.

Tests: two small embedded glTF files under jme3-plugins/src/test/resources/gltf/camera/, each with one node referencing a perspective camera. GltfLoaderTest loads them and checks the frustum of the resulting CameraNode's camera: with aspectRatio: 1.5 the frustum's right/top ratio is 1.5 (this fails on master with expected: <1.5> but was: <1.0>), and without aspectRatio it stays 1.

./gradlew :jme3-plugins:test passes (44 tests). I also built and tested the JVM modules; I couldn't run the Android modules locally (no Android SDK). The project's Checkstyle task only covers com/jme3/renderer, so it doesn't check these files; running the same checkstyle.xml on the two changed Java files reports no new warnings.

[jaime-jmebot]

Nice catch! This clean fix directly resolves the typo and adds great test coverage.

• Fixes "aspectRation" key typo in GltfLoader.java to match the glTF 2.0 specification.
• Adds unit tests covering perspective camera loading with and without aspectRatio.
• Includes lightweight test glTF files and updates gltf/README.md.