feat: add objet field (tfe/thèse/frart) with share-link restriction and site-settings toggles

TODO.md

@@ -11,4 +11,5 @@
 - [x] Extract form CSS into `form.css`; load it in admin add/edit via `$extraCss` and in student partage form directly; `system.css` now only used by `system.php`; `partage/thanks.php` rewritten to use design-system classes
 - [x] Fix student form: add missing `v_smtp_active` view to `schema.sql` (SMTP was silently skipped on fresh installs); fix `thanks.php` redirect (was `/partage/thanks.php` — blocked by nginx PHP deny rule); route `/partage/thanks` through `index.php` special-case handler
 - [x] Merge all migration SQL into schema.sql; delete migrations/ folder; simplify migrate.sh (009 share_links, 014 ap_programs, 011 apropos seed, missing semicolon fix)
+- [x] Add `objet` field (tfe/thèse/frart) to theses; `objet_restriction` on share_links; objet_these/frart_enabled site_settings; wire into partage form, parametres, and acces-etudiante
 - [x] Fix student form scroll (add `overflow-y:auto` to `.student-body`); move all remaining inline styles from partage error/password-gate pages into `form.css`