Improve the new hastily-merged PR template (#882)

## Description

### Summary

<!--Brief description of what this PR does.-->
<!--Don't explain the code, justify what this PR exists for!-->
The current template was merged too hastily by young people.
I don't like its forced length, it lacks some useful points I always use
like inline comments, and does not emphasize enough the duality between
the short, prose-written summary and the changes made as a bullet list
or check list.

<!--Sources/references at the end-->

### Issues to be resolved

<!-- If applicable-->
<!--Use keywords "closes", "fixes", "resolves", or others at
https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/using-keywords-in-issues-and-pull-requests
-->

<!--Fixes #-->
<!--Fixes aeecleclair/CalypSSO#-->

### Required PRs

<!-- If applicable-->
<!--Use keywords "depends on" or "blocked by", see
https://github.com/gregsdennis/dependencies-action -->

<!--Depends on #-->
<!--Depends on aeecleclair/CalypSSO#-->

### Changes Made

<!--Please describe the changes made in this pull request-->
<!--Tell the big steps, use a checklist to show progress. You can
explain here how the code works.-->

- [x] Two sections Description (text, actual checklist) and a
Classification, which is collapsible to keep the page not too long
- [x] Better `<!--HTML comments-->`
- [x] Description: clearly explain the diff summary/changes, and use the
order Summary (for its importance) -> relationships with issues and PRs
(for the smallness of the subsection) -> actual changes in the code
- [x] Classification: minor but useful enhancements
- [x] Removed the useless end, moved up the Additional notes

### Additional Notes

<!--Anything relevant that does not quite fit in the summary-->
Enhances #856 as intended.

<details>
<summary>

## Classification

</summary>

### Type of Change

- [ ] 🐛 Bug fix (non-breaking change which fixes an issue)
- [ ] ✨ New feature (non-breaking change which adds functionality)
- [ ] 🔨 Refactor (non-breaking change that neither fixes a bug nor adds
a feature)
- [ ] 🔧 Infra CI/CD (changes to configs of workflows)
- [ ] 💥 BREAKING CHANGE (fix or feature that require a new minimal
version of the front-end)

- [x] 😶‍🌫️ No impact for the end-users

### Impact & Scope

- [ ] Core functionality changes
- [ ] Single module changes
- [ ] Multiple modules changes
- [ ] Database migrations required

- [x] Other: PR description template <!--not module-oriented-->

### Testing

- [x] 1. Tested this locally: renders well
- [x] 2. "Added/modified tests that pass the CI": it renders well on
GitHub as well
- [ ] 3. Tested in a pre-prod

- [ ] 0. Untestable (exceptionally), will be tested in prod directly

### Documentation

- [ ] Updated [the docs](docs.myecl.fr) accordingly : <!--[Docs#0 -
Title](https://github.com/aeecleclair/myecl-documentation/pull/0)-->
- [ ] `"` Docstrings
- [ ] `#` Inline comments

- [x] No documentation needed: this *is* its self-documentation

</details>

Author: Marc-Andrieu

.github/PULL_REQUEST_TEMPLATE.md

@@ -3,52 +3,78 @@
 ### Summary
 
 <!--Brief description of what this PR does.-->
+<!--Don't explain the code, justify what this PR exists for!-->
 
-### Related Issues
+<!--Sources/references at the end-->
 
-<!-- If applicable -->
-Closes #<!--0-->
+### Issues to be resolved
 
-## Changes Made
+<!-- If applicable-->
+<!--Use keywords "closes", "fixes", "resolves", or others at https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/using-keywords-in-issues-and-pull-requests -->
+
+<!--Fixes #-->
+<!--Fixes aeecleclair/CalypSSO#-->
+
+### Required PRs
+
+<!-- If applicable-->
+<!--Use keywords "depends on" or "blocked by", see https://github.com/gregsdennis/dependencies-action -->
+
+<!--Depends on #-->
+<!--Depends on aeecleclair/CalypSSO#-->
+
+### Changes Made
 
 <!--Please describe the changes made in this pull request-->
+<!--Tell the big steps, use a checklist to show progress. You can explain here how the code works.-->
+
+- [x] ...
+- [ ] ...
+
+### Additional Notes
 
-- ...
+<!--Anything relevant that does not quite fit in the summary-->
 
-## Type of Change
+<details>
+<summary>
+
+## Classification
+
+</summary>
+
+### Type of Change
 
 - [ ] 🐛 Bug fix (non-breaking change which fixes an issue)
 - [ ] ✨ New feature (non-breaking change which adds functionality)
 - [ ] 🔨 Refactor (non-breaking change that neither fixes a bug nor adds a feature)
 - [ ] 🔧 Infra CI/CD (changes to configs of workflows)
 - [ ] 💥 BREAKING CHANGE (fix or feature that require a new minimal version of the front-end)
 
-## Impact & Scope
+- [ ] 😶‍🌫️ No impact for the end-users
+
+### Impact & Scope
 
 - [ ] Core functionality changes
 - [ ] Single module changes
 - [ ] Multiple modules changes
 - [ ] Database migrations required
-- [ ] Other
 
-## Testing
+- [ ] Other: <!--not module-oriented-->
 
-- [ ] Added/modified tests that pass the CI
-- [ ] Tested in a pre-prod
-- [ ] Tested this locally
+### Testing
 
-## Documentation
+- [ ] 1. Tested this locally
+- [ ] 2. Added/modified tests that pass the CI
+- [ ] 3. Tested in a pre-prod
 
-- [ ] Updated docs accordingly (docs.myecl.fr) : <!--[Docs#0 - Title](https://github.com/aeecleclair/myecl-documentation/pull/0)-->
-- [ ] Code includes docstrings
-- [ ] No documentation needed
+- [ ] 0. Untestable (exceptionally), will be tested in prod directly
 
-## Checklist
+### Documentation
 
-- [ ] My code follows the style guidelines of this project
-- [ ] I have commented my code, particularly in hard-to-understand areas
-- [ ] Any dependent changes have been merged and published (_Indicate the linked PR for the dependent changes_)
+- [ ] Updated [the docs](docs.myecl.fr) accordingly : <!--[Docs#0 - Title](https://github.com/aeecleclair/myecl-documentation/pull/0)-->
+- [ ] `"` Docstrings
+- [ ] `#` Inline comments
 
-## Additional Notes
+- [ ] No documentation needed
 
-Add any other context, screenshots, or information about the pull request here.
+</details>

.github/workflows/pr-dependencies.yml

@@ -0,0 +1,20 @@
+name: "PR dependencies"
+
+on:
+  pull_request:
+    types: [opened, edited, ready_for_review, synchronize]
+
+jobs:
+  pr_dependencies:
+    name: Check PR dependencies
+    runs-on: ubuntu-latest
+    permissions:
+      issues: read
+      pull-requests: read
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v5
+      - name: Check PR Dependencies
+        uses: gregsdennis/dependencies-action@main
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}