OBB: Fix applyMatrix4() with rotated boxes and negative determinants. - #35261

Related issue: -

Description

OBB.applyMatrix4() had two problems:

• The rotation extracted from the matrix was post-multiplied (rotation.multiply()), so for an OBB that already has a non-identity rotation the result was R_obb * R_matrix instead of R_matrix * R_obb. This went unnoticed because the OBB example only uses boxes with an identity rotation.
• For matrices with a negative determinant, the negated sx (used to keep the extracted rotation proper) was also applied to halfSize.x, leaving a negative half size. containsPoint() then always returns false, and intersectsOBB() gives wrong results.

const obb = new OBB( new Vector3(), new Vector3( 1, 1, 1 ) );
obb.applyMatrix4( new Matrix4().makeScale( - 1, 1, 1 ) );

obb.halfSize; // before: ( - 1, 1, 1 ), after: ( 1, 1, 1 )
obb.containsPoint( new Vector3() ); // before: false, after: true

This PR uses premultiply(), applies the absolute value of sx to the half size, and adds unit tests for both cases. The new tests fail without the fix.