feat(#131): fiches parent/AM éditable, placement AM↔enfant, statuts garde/sans_garde

Squash merge develop → master.

- Fiche parent éditable (co-parent, PATCH fiche, GET /parents)
- Fiche AM 3 onglets (PATCH fiche, rattacher/détacher enfants)
- Table enfants_assistantes_maternelles + enum garde/sans_garde
- Migration SQL + BDD.sql canonique
- Correctifs recette : @Get() parents, DTO fiche AM, fix NIR

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/routes/assistantes_maternelles/assistantes_maternelles.mapper.ts

@@ -0,0 +1,28 @@
+import { AssistanteMaternelle } from 'src/entities/assistantes_maternelles.entity';
+import { AmChildren } from 'src/entities/am_children.entity';
+import { sanitizeUserForApi } from '../../common/utils/sanitize-user-for-api';
+
+/**
+ * Sérialisation API fiche AM — ticket #131.
+ * Expose `amChildren` actifs (date_fin null) avec enfant imbriqué, sans secrets user.
+ */
+export function mapAmForApi(am: AssistanteMaternelle): AssistanteMaternelle {
+  const activeChildren = (am.amChildren ?? []).filter((link) => !link.date_fin);
+
+  return {
+    ...am,
+    user: sanitizeUserForApi(am.user)!,
+    amChildren: activeChildren.map((link) => ({
+      ...link,
+      child: link.child,
+    })),
+  };
+}
+
+export function mapAmsForApi(ams: AssistanteMaternelle[]): AssistanteMaternelle[] {
+  return ams.map(mapAmForApi);
+}
+
+export function filterActiveAmChildren(links: AmChildren[] | undefined): AmChildren[] {
+  return (links ?? []).filter((link) => !link.date_fin);
+}