feat(backend): enforce unique names and surface duplicate errors

prisma/schema.prisma

@@ -53,7 +53,7 @@ model TypeMachine {
 
 model Machine {
   id        String   @id @default(cuid())
-  name      String
+  name      String   @unique
   reference String?
   prix      Decimal? @db.Decimal(10, 2)
   createdAt DateTime @default(now())
@@ -79,7 +79,7 @@ model Machine {
 
 model Composant {
   id        String   @id @default(cuid())
-  name      String
+  name      String   @unique
   reference String?
   prix      Decimal? @db.Decimal(10, 2)
   createdAt DateTime @default(now())
@@ -101,7 +101,7 @@ model Composant {
 
 model Piece {
   id        String   @id @default(cuid())
-  name      String
+  name      String   @unique
   reference String?
   prix      Decimal? @db.Decimal(10, 2)
   createdAt DateTime @default(now())
@@ -186,7 +186,7 @@ model ModelType {
   pieces                Piece[]                           @relation("ModelTypePieceAssignments")
   pieceCustomFields     CustomField[]                     @relation("ModelTypePieceCustomFields")
 
-  @@index([category, name])
+  @@unique([category, name])
 }
 
 model Constructeur {