feat: add blueprints

[lucabello]

Add a blueprint for rocks, in order to centralize just commands and the spread.yaml file. Borrowing the rest of the PR description from the blueprints/README.md file.

Blueprints

Blueprints are shared templates for Observability components. They provide centralized files and conventions so new repositories start with consistent tooling and configuration.

Use a blueprint by copying the files into a new repository, then keep centralized files in sync via just refresh.

Available blueprints

• rocks: Shared files and workflows for Observability rock repositories. See rocks/README.md.

Customization

Blueprints define a centralize set of recipes in <blueprint>.just. These recipes can be extended or overridden in the central justfile, allowing for project-specific behaviors.

To override or extend a shared recipe, define one with the same name in justfile:

# ./justfile
set allow-duplicate-recipes
set allow-duplicate-variables
import? '<blueprint>.just'
[private]
@default:
	just --list
	echo ""
	echo "For help with a specific recipe, run: just --usage <recipe>"
# Recipe from <blueprint.just> to override
update version:
    echo "New things happen here"
# Recipe from <blueprint.just> to extend
update version:
    # Manually invoke the recipe from the centralized justfile
    just --justfile <blueprint>.just update {{version}}
    # Add your custom logic
    echo "Additional things happen here"

[mmkay]

I like it a lot, but perhaps it's also worth getting feedback from more ppl :)

[sed-i]

This is great!