Add language-search component for Autre Langue input + active search in lists

Mirrors the mots-clé tag-search system: dropdown suggestions from
existing languages via HTMX, pill display with bin-icon remove buttons,
'Créer' option for new languages. Replaces the plain text input.

- New partial: templates/partials/form/language-search.php
- New fragment: public/partage/language-search-fragment.php
- Admin wrapper: public/admin/language-search-fragment.php
- Updated language-autre-fragment to return just the required asterisk indicator
- Updated both controllers to handle language_autre as array (pill-based)
  with backward-compatible string path
- Updated edit form to compute selectedOtherLanguages from DB
- Registered new route in partage/index.php
- Fix CSV importer: split comma-separated language column into individual entries
- Add htmx active search to admin index, title line-clamp, predefined languages only in checkboxes
- Admin index: filter form now uses htmx triggers (input delay:300ms on search,
  change on selects) to actively search without page reload
- Sort links include hx-push-url for back-button support
- Added loading indicator bar (.admin-search-indicator)
- Title column: line-clamp at 2 lines with overflow hidden, native title attr
  tooltip for full text
- Language checkboxes now show only 3 predefined languages (Français, Anglais,
  Néerlandais); all others go via the Autre langue search component
- Added Database::getPredefinedLanguages() and excluded predefined from
  language-search-fragment suggestions
- Included hidden sort/dir inputs in table-wrap so sort state preserved across
  filter changes
- Fix language-search: block 'Créer' for predefined languages in dropdown
  The 'Créer' option in the language-search dropdown now also checks against the
  predefined set (français, anglais, néerlandais) to avoid offering creation of
  languages that already exist as checkboxes.

TODO.md

@@ -1,5 +1,9 @@
 # TODO
 
+- [x] Remove delete-all TFE from parametres (template, dialog, controller, DB method, logger)
+- [x] Move Formulaire + Types de travaux from parametres to contenus under Paramètres du Formulaire h2
+- [x] Restructure contenus Formulaire: sub-headings for Restrictions, Degré d'ouverture, Types de travaux, Structure
+- [x] Copy mots-clé htmx system (dropdown, pills, create) to Autre Langue input
 - [x] Languages: store lowercase, display with ucfirst (getOrCreateLanguage, CSV import, getAllLanguages, v_theses_full, schema seed data, migration 025)
 - [x] CSV importer: add AP aliases for D&P du multiple, PACS variants, Narraion typo
 - [x] Move default semantic form element styles (checkbox, radio, select) from admin.css/form.css into common.css