keras3 1.4.0

• New op_subset() and x@r[...] methods enable tensor subsetting
  using R's [ semantics and idioms.

• New subset assignment methods implemented for tensors:
  op_subset(x, ...) <- value and x@r[...] <- value

• Breaking changes: All operations prefixed with op_ now return 1-based
  indices by default. The following functions that return or consume indices have
  changed:
  op_argmax(), op_argmin(), op_top_k(), op_argpartition(),
  op_searchsorted(), op_argsort(), op_digitize(), op_nonzero(),
  op_split(), op_trace(), op_swapaxes(), op_ctc_decode(),
  op_ctc_loss(), op_one_hot(), op_arange()

• op_arange() now matches the semantics of base::seq(). By default
  it starts, includes the end value, and automatically infers step direction.

• op_one_hot() now infers num_classes if supplied a factor.

• op_hstack() and op_vstack() now accept arguments passed via ....

• application_decode_predictions() now returns a processed data frame by
  default or a decoder function if predictions are missing.

• application_preprocess_inputs() returns a preprocessor function if
  inputs are missing.

• Various new examples added to documentation,
  including op_scatter(), op_switch(), and op_nonzero().

• New x@py[...] accessor introduced for Python-style 0-based indexing of tensors.

• New Summary group generic method for keras_shape, enabling usage like
  prod(shape(3, 4))

• KERAS_HOME is now set to tools::R_user_dir("keras3", "cache") if
  ~/.keras does not exist and KERAS_HOME is unset.

• new op_convert_to_array() to convert a tensor to an R array.

• Added compatibility with Keras v3.9.2.

  • New operations added:

    • op_rot90()
    • op_rearrange() (Einops-style)
    • op_signbit()
    • op_polar()
    • op_image_perspective_transform()
    • op_image_gaussian_blur()

  • New layers introduced:

    • layer_rms_normalization()
    • layer_aug_mix()
    • layer_cut_mix()
    • layer_random_invert()
    • layer_random_erasing()
    • layer_random_gaussian_blur()
    • layer_random_perspective()

  • layer_resizing() gains an antialias argument.

  • keras_input(), keras_model_sequential(), and op_convert_to_tensor() gain a ragged argument.

  • layer$pop_layer() gains a rebuild argument and now returns the removed layer.

  • New rematerialized_call() method added to Layer objects.

  • Documentation improvements and minor fixes.

• Fixed an issue where op_shape() would sometimes return a TensorFlow TensorShape

• Fixes for metric_iou(), op_top_k(), and op_eye() being called with R atomic doubles