fix(#131): aligner PATCH fiche AM back sur le payload front

Étend UpdateAmFicheAdminDto (nir, date/lieu naissance, agreement_date)
et persiste ces champs dans updateFicheAdmin avec validation NIR.

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

backend/src/routes/assistantes_maternelles/dto/update-am-fiche-admin.dto.ts

@@ -1,6 +1,7 @@
 import { ApiPropertyOptional } from '@nestjs/swagger';
 import {
   IsBoolean,
+  IsDateString,
   IsEmail,
   IsEnum,
   IsInt,
@@ -59,12 +60,40 @@ export class UpdateAmFicheAdminDto {
   @IsEnum(StatutUtilisateurType)
   statut?: StatutUtilisateurType;
 
+  @ApiPropertyOptional({ example: '123456789012345' })
+  @IsOptional()
+  @IsString()
+  @MaxLength(15)
+  nir?: string;
+
+  @ApiPropertyOptional({ example: '1985-03-12' })
+  @IsOptional()
+  @IsDateString()
+  date_naissance?: string;
+
+  @ApiPropertyOptional({ example: 'Lyon' })
+  @IsOptional()
+  @IsString()
+  @MaxLength(100)
+  lieu_naissance_ville?: string;
+
+  @ApiPropertyOptional({ example: 'France' })
+  @IsOptional()
+  @IsString()
+  @MaxLength(100)
+  lieu_naissance_pays?: string;
+
   @ApiPropertyOptional({ example: 'AGR-2024-12345' })
   @IsOptional()
   @IsString()
   @MaxLength(50)
   approval_number?: string;
 
+  @ApiPropertyOptional({ example: '2020-01-15' })
+  @IsOptional()
+  @IsDateString()
+  agreement_date?: string;
+
   @ApiPropertyOptional({ example: 'Lyon' })
   @IsOptional()
   @IsString()