Add CI job to ensure practice exercise order

.github/workflows/order-of-practice-exercises.yml

@@ -0,0 +1,16 @@
+name: Ensure practice exercise order
+
+on:
+  pull_request:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  call-gha-workflow:
+    name: check
+    uses: exercism/github-actions/.github/workflows/sorted.yml@main
+    with:
+      ordering: ".difficulty, .lowercase_name"

README.md

@@ -13,6 +13,7 @@ The following system dependencies are required:
 - [`bash` shell][gnu-bash].
 - PHP V8.4+ CLI.
 - An active Internet connection for installing required tools / composer packages.
+- [`jq`][jq], if you change the difficulty or add a practice exercise.
 
 Run the following command to get started with this project:
 
@@ -90,6 +91,8 @@ contribution/generator/bin/console app:create-tests '<slug>'
 composer lint:fix
 ```
 
+Run `bin/order-exercises.sh` when you set the exercise difficulty to a sensible value to order the exercises on the website accordingly.
+
 [exercism-configlet]: https://exercism.org/docs/building/configlet
 [exercism-docs]: https://exercism.org/docs
 [exercism-track-home]: https://exercism.org/docs/tracks/php
@@ -98,3 +101,4 @@ composer lint:fix
 [gnu-bash]: https://www.gnu.org/software/bash/
 [local-file-phpcs-config]: phpcs.xml
 [psr-12]: https://www.php-fig.org/psr/psr-12
+[jq]: https://jqlang.org/

bin/order-exercises.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+# matches ".difficulty, .lowercase_name" in .github/workflows/order-of-practice-exercises.yml
+
+jq '
+    .exercises.practice |= (
+        map(if .slug == "hello-world" then .difficulty = -1 else . end)
+        | sort_by(.difficulty, (.name|ascii_downcase))
+        | .[0].difficulty = 1
+    )
+' config.json > config.sorted && mv config.sorted config.json