Add Device.arch property for convenient compute capability string access - #877

This PR adds a convenient Device.arch property that returns the compute capability as a concatenated string, eliminating the need for repetitive string concatenation code throughout the codebase.

Problem

Previously, getting the compute capability as a string required this verbose pattern everywhere:

arch = "".join(f"{i}" for i in dev.compute_capability)
program_options = ProgramOptions(std="c++17", arch=f"sm_{arch}")

This pattern appeared in 8 locations across 7 example files and was identified as annoying repetitive code.

Solution

Added a new arch property to the Device class:

@property
def arch(self) -> str:
    """Return compute capability as a string (e.g., '75' for CC 7.5)."""
    return "".join(f"{i}" for i in self.compute_capability)

Now the usage is much cleaner:

arch = dev.arch
program_options = ProgramOptions(std="c++17", arch=f"sm_{arch}")

Changes

• Added Device.arch property in cuda_core/cuda/core/experimental/_device.py
• Updated 8 occurrences across 7 example files to use the new property:
  • cuda_core/examples/vector_add.py
  • cuda_core/examples/simple_multi_gpu_example.py (2 occurrences)
  • cuda_core/examples/pytorch_example.py
  • cuda_core/examples/strided_memory_view_gpu.py
  • cuda_core/examples/saxpy.py
  • cuda_core/examples/cuda_graphs.py
  • cuda_core/examples/memory_ops.py
• Added comprehensive test for the new property in test_device.py
• Preserved existing test files unchanged as requested

Benefits

• More concise and readable code
• Eliminates repetitive string concatenation
• Provides a clear, discoverable API
• Maintains full backward compatibility
• Works correctly with all compute capability values (tested with edge cases)

Fixes #729.

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