refactor: rename "folder" to "package" throughout codebase

- Rename CSS files: _card-folder.scss → card-package
- Rename template files: _folder.scss → package
- Update all CSS class names and selectors
- Delete old folder blueprints and templates
- Add new package blueprints with improved structure
- Update investigation-summary template and blueprint
- Add "Dossiers" menu item in panel configuration
- Improve package blueprint with linkedContent field

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

site/templates/packages.php

@@ -0,0 +1,59 @@
+<?php snippet('header') ?>
+<main>
+
+<header class="page__header">
+
+    <h2 class="page__title"><?= $page->title() ?></h2>
+
+    <?php if ($page->chapo()->isNotEmpty()): ?>
+    <div class="description-medium">
+        <p><?= $page->chapo() ?></p>
+    </div>
+    <?php endif ?>
+</header>
+
+<section class="container-cards">
+
+
+
+<?php foreach ($page->children()->listed() as $package): ?>
+<article class="card--package">
+
+    <?php if ($cover = $package->cover()->toFile()): ?>
+    <figure>
+        <img src="<?= $cover->url() ?>" alt="<?= $package->title()->esc() ?>">
+    </figure>
+    <?php endif ?>
+
+    
+
+    <div class="content">
+        <h4 class="title"><a href="<?= $package->url() ?>"><span class="icon"><?= svg('assets/icons/package.svg') ?></span><?= $package->title()->esc() ?></a></h4>
+
+        <?php if ($package->description()->isNotEmpty()): ?>
+        <p class="short"><?= $package->description()->excerpt(200) ?></p>
+        <?php endif ?>
+
+        <?php
+        // Compter les enquêtes associées à ce dossier
+        $investigationsCount = site()->find('enquetes')->children()->listed()->filter(function($investigation) use ($package) {
+            return $investigation->package()->value() === $package->slug();
+        })->count();
+        ?>
+
+            <ul>
+                <?php if ($investigationsCount > 0): ?>
+                    <li><?= $investigationsCount ?> enquête<?= $investigationsCount > 1 ? 's' : '' ?></li>
+                <?php endif ?>
+                    <li>8 impacts</li>
+                </ul>
+
+    </div>
+    <button class="btn--go-to"><a href="#" target="_blank"><?= svg('assets/icons/arrow-left.svg') ?></a></button>
+    <a class="link-block" href="<?= $package->url() ?>"></a>
+</article>
+<?php endforeach ?>
+
+</section>
+</main>
+<?php snippet('footer') ?>