Add .gitignore entries when running astro add <adapter>

[alexanderdombroski]

Summary

Add .gitignore entries when adding adapters via the astro add command.

Background & Motivation

Many adapters include generated types or build output that shouldn't be version controlled. This currently has to be configured manually each project. Astro should automate and standardize this behavior to provide these benefits:

• Removal of repetitive architectural decisions
• Reduced onboarding friction
• A consistent default that prevents repository inconsistency

There is already code for this when running astro add vercel.

Goals

These entries could be added to the .gitignore:

Cloudflare: .wrangler/ and worker-configuration.d.ts.
Netlify: .netlify/

Proposal Champion

I would be happy to create a PR for this.

[florian-lefebvre]

PR definitely welcome!

[alexanderdombroski]

Great, here is the PR!