[Feature]: Avoid modifying existing codes/configs when init modernjs from an existing repo

[yf-yang]

What problem does this feature solve?

I am trying to convert a module repo to modern.js module, so I run pnpm create @modern-js, it is the recommended way to init an existing repo. Actually it does the following:

1. Update package.json (overrides everything)
2. Update src/index.ts
3. Commit working changes

Change 1 is unpleasing as existing repo has its own dependencies, scripts...
Change 2/3 are unexpected. Editors could have caches and those changes are not even explicitly notified, so I spent hours figuring out if rspack etc. have bugs.

Suggestion:

1. When enabling modern.js in an existing repo, do incremental change instead of complete overwrite.
2. Notify the file changes, git commits, and anything else that I haven't even observed.

What does the proposed API look like?

Nope

[caohuilin]

@modern-js/create is not expected to be executed directly in an existing project. During the automatic project creation process, existing files will be overwritten. The best way to use it is to create a new project with @modern-js/create and then move the existing code there.