Feature request: Generate .gitignore during npx campaign-init

[masmalsah]

Summary

npx campaign-init sets up _data/campaigns.json and npm scripts, but doesn't generate a .gitignore. Developers have to create one manually or risk committing build output, editor files, and local config.

Proposed Solution

Generate a .gitignore as part of npx campaign-init (or prompt to create one if it doesn't already exist):

**/.DS_Store
.AppleDouble
.LSOverride
node_modules/
_site/
.tmp/
scss/
**/.sass-cache
/.sass-cache/
.vscode/
.cursor/

Local Netlify folder
.netlify

If a .gitignore already exists, skip or prompt rather than overwrite.

Why

_site/ (the build output) and node_modules/ are the critical ones — easy to accidentally commit without a .gitignore in place. The rest covers common editor and OS clutter that most projects exclude anyway.

[alexphelps]

@masmalsah A proper .gitignore should be part of starter templates and repos using page kit but not a feature of page kit itself. A future create campaign to initialize a campaign from a template might include a .gitignore but we'll cross that bridge when we get there.