refactor: decouple format extras from main fichiers block, scope FilePond destroy to individual slots, fix FilePond integration for decoupled extras

TODO.md

@@ -20,3 +20,6 @@
   - [x] Update admin/add.php, admin/edit.php, partage/index.php: swap sortable+file-upload-queue for filepond
   - [x] Remove file-upload-queue.js and sortable.min.js
   - [x] Clean up CSS: remove .fq-*, .tfe-file-queue styles, add filepond.css + theme overrides
+  - [x] Decouple format extras from main file inputs — slot-based HTMX swaps preserve FilePond instances
+  - [x] Fix initFilePonds → window.XamxamInitFilePonds bug
+  - [x] Verify backend $_FILES['queue_file'][*] data flow unchanged