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/blueprints/pages/investigation-summary.yml

@@ -88,7 +88,7 @@ tabs:
     label: Métadonnées
     icon: table
     fields:
-      folder:
+      package:
         label: Dossier
         type: select
         options: query

site/blueprints/pages/package.yml

@@ -5,18 +5,22 @@ tabs:
     label: Contenu
     icon: page
     fields:
-      description:
-        label: Description
-        type: textarea
-        size: medium
-        buttons: false
       cover:
         label: Visuel de couverture
         type: files
         multiple: false
         layout: cards
+        width: 1/3
         image:
           ratio: 12/7
           cover: true
         help: Image utilisée dans la liste des dossiers
+      description:
+        label: Description
+        type: writer
+        width: 2/3
+      linkedContent:
+        label: Contenu
+        type: pages
+        query: site.find('enquetes').children
   seo: seo/page

site/blueprints/pages/packages.yml

@@ -4,15 +4,16 @@ tabs:
   contentTab:
     label: Contenu
     sections:
-      folders:
+      packages:
+        label: Dossiers
         type: pages
         text: "{{ page.title }}"
-        info: "{{ page.description }}"
+        info: "{{ page.linkedContent.toPages.count }} contenus"
         layout: cards
         size: huge
         search: true
         image:
           cover: true
           ratio: 12/7
-        template: folder
+        template: package
   seo: seo/page