feat: update database schema to use snake_case for table names and add mapping for models

apps/api/prisma/schema.prisma

@@ -24,6 +24,8 @@ model User {
   groupsMember   Member[]
   groupsOwner    Group[]      @relation("OwnerGroups")
   waitlist       WaitlistEntry[]
+
+  @@map("users")
 }
 
 model Account {
@@ -44,6 +46,7 @@ model Account {
   user User @relation(fields: [userId], references: [id], onDelete: Cascade)
 
   @@unique([providerId, providerAccountId])
+  @@map("accounts")
 }
 
 model Session {
@@ -57,6 +60,8 @@ model Session {
   updatedAt DateTime @updatedAt
 
   user User @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+  @@map("sessions")
 }
 
 model Verification {
@@ -68,6 +73,7 @@ model Verification {
   updatedAt  DateTime @updatedAt
 
   @@unique([identifier, value])
+  @@map("verifications")
 }
 
 // Domain models
@@ -83,6 +89,8 @@ model Group {
   members  Member[]
   students Student[]
   payments Payment[]
+
+  @@map("groups")
 }
 
 model Member {
@@ -96,6 +104,7 @@ model Member {
   user  User  @relation(fields: [userId], references: [id], onDelete: Cascade)
 
   @@unique([groupId, userId])
+  @@map("members")
 }
 
 enum Role {
@@ -120,6 +129,7 @@ model Student {
   payments Payment[]
 
   @@index([groupId])
+  @@map("students")
 }
 
 model Payment {
@@ -139,6 +149,7 @@ model Payment {
 
   @@index([groupId])
   @@index([studentId])
+  @@map("payments")
 }
 
 enum PaymentStatus {
@@ -161,6 +172,7 @@ model WaitlistEntry {
   user User? @relation(fields: [userId], references: [id], onDelete: SetNull)
 
   @@unique([email])
+  @@map("waitlist_entries")
 }
 
 enum WaitlistStatus {