[Feature Request]: Install package from CRAN instead of github releases

### Feature description

It seems odd that we use github as the source for packages on `teal.gallery` apps that users are encouraged to tweak.

- `stable` versions should use CRAN versions whenever possible.
- Packages not released on CRAN may need a custom exception mechanism that indicates the github repository (could be a named list with `package = "/"`)
- `dev` could use [insights.engineering.r-universe.dev](insights.engineering.r-universe.dev) repository as part of the repos

This needs further refining and discussion with previous maintaner

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct.

### Contribution Guidelines

- [x] I agree to follow this project's Contribution Guidelines.

### Security Policy

- [x] I agree to follow this project's Security Policy.

No files, tests, or entry points are named. Start by locating where stable and dev package repositories are configured, then clarify the exception format with the previous maintainer. Done means stable apps use CRAN whenever possible, dev apps include insights.engineering.r-universe.dev, and non-CRAN packages have a defined GitHub exception mechanism.

Written by the indexing model from the issue text.