chore(just): add a _default recipe

Author: luisschwab

justfile

@@ -4,6 +4,9 @@ alias f := fmt
 alias t := test
 alias p := pre-push
 
+_default:
+   @just --list
+
 # Build the project
 build:
    cargo build
@@ -26,4 +29,4 @@ test:
    cargo test --workspace --exclude 'example_*' --all-features
 
 # Run pre-push suite: format, check, and test
-pre-push: fmt check test
+pre-push: fmt check test