Refactor + feat: unify format/fichiers HTMX fragment, reorder format types, add file constraints, fix admin auth

* **Unified Format + Fichiers into a single HTMX fragment**

  * Introduced `app/public/partage/fichiers-fragment.php` as shared dynamic block returning both format checkboxes and adaptive “Fichiers” fieldset
  * Logic adapts inputs based on selected formats:

    * no selection / upload formats → standard file inputs
    * “Site web” → URL fields only
    * “Site web + upload” → file inputs + URL sub-fieldset
  * Added admin wrapper: `app/public/admin/fichiers-fragment.php` (gated via `admin_mode=1`)
  * Added `app/public/admin/format-website-fragment.php` for edit-mode website URL toggling
  * Wired route `/partage/fichiers-fragment` in `app/public/partage/index.php`
  * Refactored `form.php` (add/edit partage) to use single `#format-fichiers-block` instead of separate fragments
  * Edit mode format checkboxes now target `format-website-fragment.php` → `#edit-website-url-fieldset`
  * Added `$hxInclude` support in `checkbox-list.php` for configurable HTMX includes

* **Format system migration + ordering**

  * Migration `020_format_types_sort_and_rename.sql`:

    * added `sort_order` column to `format_types`
    * inserted new format **Image**
    * defined ordering: Écriture · Image · Audio · Vidéo · Site web · Performance · Objet éditorial · Installation · Autre
  * `Database.php`: format queries now use `ORDER BY sort_order, id`
  * `fichiers-fragment.php`:

    * uses ordered format list
    * resolves Image/Vidéo/Audio by name
    * introduces `$hasImage` flag
    * preserves `admin_mode` across HTMX requests

* **File constraints and UX updates**

  * Enforced **100 MB PDF limit**

    * `ThesisCreateController`: `MAX_PDF_SIZE = 100MB` for PDFs only
    * `ThesisEditController`: same PDF-specific constraint applied
    * Other file types remain capped at 500 MB
  * Updated UI hints in `fichiers-fragment.php` and edit form:

    * explicitly mention 100 MB PDF limit
    * added reference to `bentopdf.com` for compression guidance
  * `file-field.php`: added `$hintRaw` to allow HTML rendering in hints

* **Admin authentication fix**

  * Fixed missing auth in admin fragments
  * Added `require_once AdminAuth.php`
  * Replaced direct usage with `AdminAuth::requireLogin()`
  * Applied consistent pattern with existing fragment authentication approach

* **Migrations included**

  * `019_add_ecriture_format.sql`
  * `020_format_types_sort_and_rename.sql`

* **Files affected**

  * Controllers: `ThesisCreateController`, `ThesisEditController`
  * DB layer: `Database.php`
  * Public fragments: `partage/fichiers-fragment.php`, `admin/fichiers-fragment.php`, `admin/format-website-fragment.php`
  * Templates: `form.php`, `checkbox-list.php`, `file-field.php`
  * Routing: `partage/index.php`
  * Misc: `TODO.md`

This consolidates format normalization, HTMX UI simplification, file validation rules, and admin stability fixes into a single coherent system update.

app/src/Controllers/ThesisCreateController.php

@@ -23,6 +23,9 @@ class ThesisCreateController
     /** Maximum allowed file size for thesis files (bytes). */
     private const MAX_FILE_SIZE = 500 * 1024 * 1024; // 500 MB
 
+    /** Maximum allowed file size for PDF files specifically (bytes). */
+    private const MAX_PDF_SIZE = 100 * 1024 * 1024; // 100 MB
+
     /** MIME types accepted for thesis files. */
     private const ALLOWED_MIME_TYPES = [
         // Images
@@ -640,8 +643,10 @@ class ThesisCreateController
                 continue;
             }
 
-            if ($uploads['size'][$i] > self::MAX_FILE_SIZE) {
-                error_log("ThesisCreateController: file too large {$uploads['name'][$i]}, skipping");
+            $isPdf = ($mimeType === 'application/pdf' || $ext === 'pdf');
+            $sizeLimit = $isPdf ? self::MAX_PDF_SIZE : self::MAX_FILE_SIZE;
+            if ($uploads['size'][$i] > $sizeLimit) {
+                error_log("ThesisCreateController: file too large {$uploads['name'][$i]} (" . round($uploads['size'][$i] / 1024 / 1024) . ' MB), skipping');
                 continue;
             }