META Create a reference Gno project setup

[moul]

This new repo will serve as a template for starting Gno projects with best practices and proper tooling baked in. It should help contributors or teams quickly scaffold a real-world Gno setup.

Initial scope (MVP)

We want this template to:

• Handle installing Go & Gno dependencies.
• Run gnodev with a minimal default realm.
• Run gno test ./... from the Makefile.
• Run gno lint and validate formatting.
• Be integrated with a basic CI workflow (e.g. GitHub Actions).
• Support both p/ and r/ structure.
• Allow declaring and using external dependencies (outside this repo).

Bonus

We want this repo to feel like a base you’d want to fork or clone when building serious apps. It doesn’t need to showcase app logic — it’s about tooling, layout, and good habits.

[moul]

I think that we depend on

• gno.mod refactor (feat: transpile to Gno 0.9 (latest interrealm spec) with @cross gno#4264)
• feat(gnovm): packages loader gno#2932

To go beyond simple cases, such as having several local packages while at the same time depending on examples/ folder.

cc @n0izn0iz @gfanton what do you think?