feat(template): per-experiment daily record template — rename/add/hide fields, custom_fields JSONB

backend/prisma/schema.prisma

@@ -12,6 +12,7 @@ model Experiment {
   id         String   @id @default(uuid())
   title      String
   created_at DateTime @default(now())
+  template   Json     @default("[]")
   animals    Animal[]
 
   @@map("experiments")
@@ -36,6 +37,7 @@ model DailyStatus {
   vitals                 String?
   treatment              String?
   notes                  String?
+  custom_fields          Json?
   animal                 Animal   @relation(fields: [animal_id], references: [id], onDelete: Cascade)
 
   @@map("daily_statuses")