fix: Windows ENOENT by enabling shell resolution for Shopify CLI

[Xurya]

Summary

• Adds shell: true on Windows when spawning the Shopify CLI to fix ENOENT failures.
• Scope-limited to Windows; Linux/macOS behavior remains unchanged.

Problem

• On Windows, spawn('shopify', ...) can fail with ENOENT even when shopify.cmd exists and where shopify resolves it.
• Node’s spawn does not resolve .cmd without a shell, causing CLI commands (build/info) to fail under certain PATH/env conditions.

Fix

• Set shell: true on Windows for the shopify child process as a fallback.

Rationale

• Minimal, targeted change that unblocks Windows users immediately.
• Arguments are passed as an array (not a single shell-joined string), reducing typical shell-injection risks.
• No impact on non-Windows platforms.

Validation

• Verified on Windows with both global and local CLI installations:
  • ENOENT error resolved; build and info commands succeed under tests.
• Confirmed no behavior change on non-Windows platforms.

Note

Please test extensively, modify as needed. I've only tested on my local machines and environments (one Windows and one macOS Tahoe v26.0.1)

Potential Improvements / Alternatives

• Support override (ie SHOPIFY_CLI_PATH to explicitly point at the CLI binary.
• Prefer local CLI and spawn that absolute path with shell: false. If local CLI not found, use global shopify with shell: true only on Windows.
• On ENOENT/non-zero exit, include cwd, chosen CLI path, and actionable guidance (e.g., install local CLI or set override).

[Xurya]

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