Proposal: change the --port flag of remix dev to a more-specific name (e.g., --hot-update-port)

[leothorp]

As documented in https://remix.run/docs/en/main/other-api/dev#setting-a-custom-port, remix dev uses the --port flag to configure the hot update port. This diverges from the majority of other JS frameworks that include a dev server, which have typically stuck to the convention of using --port to specify the port the application is running on (examples: Vite, Next.js, Vue, Angular, Svelte, Astro, Gatsby, create-react-app, and likely others).

By going against this convention with remix dev, I'd argue there's risk of needless confusion for new developers coming from any of these other tools. Beyond that, Remix itself already overloads the --port term to refer to the application port with remix-serve. It's true that they are technically separate commands, but because remix dev calls out to remix-serve by default, the lines are blurred, and it feels like the kind of subtle distinction that isn't helpful for people to have to remember. There's a paragraph in the docs needed just to clarify the difference between the two usages of the same flag.

So the proposal here is just renaming the remix dev --port flag to something more specific that indicates its purpose- for example, remix dev --hot-update-port. Going one further, it'd also be nice to add a more familiar --port flag which sets the app port, but that's less necessary if there isn't the pitfall of the existing flag anymore.