feat: add open command

[zenorocha]

Summary by cubic

Adds an open command that launches https://resend.com/emails in your default browser on macOS, Windows, and Linux, with help text and a Windows start fix.

^{Written for commit e893bac. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 2 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/commands/open.ts">

<violation number="1" location="src/commands/open.ts:16">
P2: On Windows, `start` is a CMD internal command, not an executable, so `Bun.spawn(['start', url])` will fail. Invoke it via `cmd /c start` (or use `explorer`) so the open command works on Windows.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}