feat(#152/#155): cleanup est_multiple + dashboard sans préfixe Admin (squash develop).

Suppression complète grossesse multiple / est_multiple (BDD, API, front).
Rename option C : widgets partagés et panels staff sous widgets/dashboard/,
AdminManagementWidget seul restant dans widgets/admin/.

tests/scripts/register-parent-martin-test.mjs

@@ -46,8 +46,7 @@ const body = {
       date_naissance: '2023-02-15',
       genre: 'F',
       photo_base64: toDataUri(path.join(photosDir, 'martin-emma.png')),
-      photo_filename: 'emma_martin.png',
-      grossesse_multiple: true,
+      photo_filename: 'emma_martin.png'
     },
     {
       prenom: 'Noah',
@@ -55,8 +54,7 @@ const body = {
       date_naissance: '2023-02-15',
       genre: 'H',
       photo_base64: toDataUri(path.join(photosDir, 'martin-noah.png')),
-      photo_filename: 'noah_martin.png',
-      grossesse_multiple: true,
+      photo_filename: 'noah_martin.png'
     },
     {
       prenom: 'Léa',
@@ -64,8 +62,7 @@ const body = {
       date_naissance: '2023-02-15',
       genre: 'F',
       photo_base64: toDataUri(path.join(photosDir, 'martin-lea.png')),
-      photo_filename: 'lea_martin.png',
-      grossesse_multiple: true,
+      photo_filename: 'lea_martin.png'
     },
   ],
   presentation_dossier: presentationDossier,