fix: make --device flag case-insensitive consistent with other commands (#215)

[DingmaomaoBJTU]

Summary

winml analyze --device only accepted uppercase (NPU, GPU, CPU). All other commands (compile, eval, perf, config) accept lowercase. This single-character fix makes the device_option() helper consistent.

Change

src/winml/modelkit/utils/cli.py:81 — case_sensitive=True → case_sensitive=False

click.Choice with case_sensitive=False normalizes the user input to match the canonical form in the choices list ("npu" → "NPU"), so no downstream code changes are needed.

Before / After

Before — lowercase input fails:

$ winml analyze --model model.onnx --ep qnn --device npu
Error: Invalid value for '--device': 'npu' is not one of 'CPU', 'GPU', 'NPU'.

$ winml analyze --model model.onnx --ep qnn --device gpu
Error: Invalid value for '--device': 'gpu' is not one of 'CPU', 'GPU', 'NPU'.

After — any casing accepted, value normalized to uppercase:

$ winml analyze --model model.onnx --ep qnn --device npu   # ✓ device=NPU
$ winml analyze --model model.onnx --ep qnn --device NPU   # ✓ device=NPU
$ winml analyze --model model.onnx --ep qnn --device gpu   # ✓ device=GPU
$ winml analyze --model model.onnx --ep qnn --device Gpu   # ✓ device=GPU

Closes #215