bugfix: add support for underscore in project name for generated files

[Themelok]

Summary

Fixes #295

When creating a new project with hyphens in the name using sf new some-new-project, the generated Cargo.toml was using the hyphenated name for the library target, causing compilation to fail with:

error: failed to parse manifest at `Cargo.toml`

Caused by:
  library target names cannot contain hyphens

[graphite-app]

Graphite Automations

"Star Frame: Request reviewers" took an action on this PR • (11/12/25)

1 reviewer was added to this PR based on Brett Etter's automation.

[stegaBOB]

Looks good! Eventually we're going to want to migrate to an actual templating library. Would probably make sense to use cargo_generate like how dioxus and other cli tools do it: https://github.com/DioxusLabs/dioxus/blob/bd2d1de873ae9c0e7c4656ec0c991ea9aafd3293/packages/cli/src/cli/init.rs#L89

For now though, this looks good to me!

[stegaBOB]

@Themelok can you add a changelog entry for this PR too? Thanks