feat(auth): add initial Prisma schema for user authentication

.gitignore

@@ -40,7 +40,10 @@ yarn-error.log*
 next-env.d.ts
 
 # cache
-cache
+/cache
 
 # bun
 bun.lockb
+
+# prisma
+/prisma/migrations

prisma/schema.prisma

@@ -0,0 +1,78 @@
+datasource db {
+    provider = "postgresql"
+    url      = env("DATABASE_URL")
+}
+
+generator client {
+    provider = "prisma-client-js"
+}
+
+model User {
+    id            String          @id @default(cuid())
+    name          String?
+    email         String          @unique
+    emailVerified DateTime?
+    image         String?
+    accounts      Account[]
+    sessions      Session[]
+    // Optional for WebAuthn support
+    Authenticator Authenticator[]
+
+    createdAt DateTime @default(now())
+    updatedAt DateTime @updatedAt
+}
+
+model Account {
+    userId            String
+    type              String
+    provider          String
+    providerAccountId String
+    refresh_token     String?
+    access_token      String?
+    expires_at        Int?
+    token_type        String?
+    scope             String?
+    id_token          String?
+    session_state     String?
+
+    createdAt DateTime @default(now())
+    updatedAt DateTime @updatedAt
+
+    user User @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+    @@id([provider, providerAccountId])
+}
+
+model Session {
+    sessionToken String   @unique
+    userId       String
+    expires      DateTime
+    user         User     @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+    createdAt DateTime @default(now())
+    updatedAt DateTime @updatedAt
+}
+
+model VerificationToken {
+    identifier String
+    token      String
+    expires    DateTime
+
+    @@id([identifier, token])
+}
+
+// Optional for WebAuthn support
+model Authenticator {
+    credentialID         String  @unique
+    userId               String
+    providerAccountId    String
+    credentialPublicKey  String
+    counter              Int
+    credentialDeviceType String
+    credentialBackedUp   Boolean
+    transports           String?
+
+    user User @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+    @@id([userId, credentialID])
+}