Handle Windows npx detection when npx.cmd is missing

[jlowin]

Motivation

• On Windows, _get_npx_command() probed npx.cmd, npx.exe, and npx using subprocess.run(..., shell=False), but only caught subprocess.CalledProcessError, so a missing executable raised FileNotFoundError and aborted the probe early instead of falling back to the next candidate.

Description

• Continue probing when the candidate binary is absent by catching FileNotFoundError in the same except block as CalledProcessError, and add a focused unit test test_get_npx_command_windows_cmd_missing that simulates FileNotFoundError for npx.cmd and verifies fallback to npx.exe.

Before/after (conceptual):
except subprocess.CalledProcessError: -> except (subprocess.CalledProcessError, FileNotFoundError):

Testing

• Ran uv sync (succeeded), ran the full test suite uv run pytest -n auto (environment showed unrelated timeouts/integration failures outside this CLI change), and ran the focused CLI tests with uv run pytest tests/cli/test_cli.py -k npx_command which passed (6 passed); uv run prek run --all-files failed to init hooks due to external network access to a git dependency.

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Codex Task