fix: restore Wally root module

[cayasde]

Summary

• restore default.project.json in the Wally package
• map the package root directly to src
• add a patch changeset

Root cause

Without a root Rojo project, the package directory becomes a Folder in a Pesde + Rojo project. Pesde's Wally linker requires that directory directly, so require fails. The previous project instead produced a DataModel wrapper.

Validation

• wally package --list
• rojo sourcemap default.project.json (ok is a ModuleScript)
• npm run build:rbxm
• npm run check
• npm test