CMake: drop invalid OPTIONAL from Cycles runtime-deps install

install(DIRECTORY) disallows OPTIONAL together with FILES_MATCHING, which
broke reconfigure. The directory is always present here (produced by the
CyclesBuild step), so OPTIONAL was unnecessary.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CMakeLists.txt

@@ -402,11 +402,12 @@ if(OPENUSD_HAS_CYCLES)
         DESTINATION bin/usd
         OPTIONAL
     )
-    # Cycles runtime deps (embree4, epoxy, imath, openvdb, OIDN, sycl, etc.)
+    # Cycles runtime deps (embree4, epoxy, imath, openvdb, OIDN, sycl, etc.).
+    # No OPTIONAL: install(DIRECTORY) disallows it with FILES_MATCHING, and the
+    # dir always exists here since it is produced by the CyclesBuild step.
     install(DIRECTORY "${CYCLES_INSTALL_DIR}/"
         DESTINATION bin
         FILES_MATCHING PATTERN "*.dll"
-        OPTIONAL
     )
     # tbb12.dll (used by openvdb/embree4) lives in the precompiled lib tree, not install output
     install(FILES "${CYCLES_TBB12_DLL}"

src/ui/TransformManipulator.cpp

@@ -645,11 +645,21 @@ bool TransformManipulator::HandleInput(const pxr::GfMatrix4d& vp,
                     ? deltaM * m_dragRotateInitialRotMat
                     : m_dragRotateInitialRotMat * deltaM;
 
-                // usdtweak: GfRotation::DecomposeRotation(resultingRotation,
-                //             pxAxis, pyAxis, pzAxis, 1.0, &tw, &fb, &lr, &sw, true)
-                const pxr::GfVec3d pxA=m_dragRotateInitialRotMat.GetRow3(0);
-                const pxr::GfVec3d pyA=m_dragRotateInitialRotMat.GetRow3(1);
-                const pxr::GfVec3d pzA=m_dragRotateInitialRotMat.GetRow3(2);
+                // Decompose `result` (the new total local rotation matrix) back
+                // into XformCommonAPI Euler angles.
+                //
+                // SetRotate() interprets the written angles as rotations about the
+                // CANONICAL x/y/z axes, so the decompose axes MUST be canonical.
+                // The previous port used the rows of initRot here -- i.e. the prim's
+                // already-rotated frame -- which equals the canonical axes only when
+                // the prim is at zero rotation.  That mismatch is exactly why the
+                // authored result desynced from the manipulator once the prim already
+                // carried a rotation: the angles were measured in the rotated frame
+                // but written as if they were canonical-frame angles.
+                //
+                // (Decomposition assumes RotationOrderXYZ -- the XformCommonAPI
+                //  default; non-XYZ orders are mapped tw->X, fb->Y, lr->Z as before.)
+                static const pxr::GfVec3d kCanonX(1,0,0), kCanonY(0,1,0), kCanonZ(0,0,1);
 
                 double tw=pxr::GfDegreesToRadians(double(m_dragStartRotate[0]));
                 double fb=pxr::GfDegreesToRadians(double(m_dragStartRotate[1]));
@@ -657,7 +667,7 @@ bool TransformManipulator::HandleInput(const pxr::GfMatrix4d& vp,
                 double sw=0;
 
                 pxr::GfRotation::DecomposeRotation(
-                    result,pxA,pyA,pzA,1.0,&tw,&fb,&lr,&sw,/*useHint=*/true);
+                    result,kCanonX,kCanonY,kCanonZ,1.0,&tw,&fb,&lr,&sw,/*useHint=*/true);
 
                 pxr::GfVec3f newRot(float(pxr::GfRadiansToDegrees(tw)),
                                     float(pxr::GfRadiansToDegrees(fb)),