Show dart pub add --dev for development-only packages

[shinriyo]

Summary

Some packages are intended to be used only as development dependencies, such as code generators, linters, and testing tools.

However, the Install tab on pub.dev always generates a regular install command, for example:

dart pub add build_runner

This can mislead users into adding development-only packages to dependencies instead of dev_dependencies.

Examples

Examples of packages that are typically added as development dependencies:

• build_runner
• flutter_lints
• test
• riverpod_generator

For these packages, the recommended command would instead be:

dart pub add dev:build_runner

(or the equivalent command for the current supported syntax).

Proposal

Allow package authors to indicate that a package is intended to be installed as a development dependency.

pub.dev could then generate the appropriate install command automatically for those packages.

This would only affect the generated installation instructions and would not prevent users from installing the package as a regular dependency if they intentionally choose to do so.

Motivation

Many beginners simply copy and paste the generated command from the Install tab.

Providing the recommended command would help users follow best practices and reduce accidental misuse of development-only packages.