feat: add initial backend and frontend structure with models, DTOs, and WebSocket events

apps/backend/prisma/models/character.prisma

@@ -0,0 +1,56 @@
+// Character model and character knowledge
+
+enum ImportSourceType {
+  file
+  url
+  manual
+}
+
+enum ImportStatus {
+  pending
+  processing
+  completed
+  failed
+}
+
+model Character {
+  id                  String   @id @default(uuid())
+  name                String
+  avatarUrl           String?
+  personalityPrompt   String
+  attributes          Json     @default("{}")
+  config              Json     @default("{}")
+  isPublic            Boolean  @default(false)
+  createdAt           DateTime @default(now())
+  updatedAt           DateTime @updatedAt
+
+  userId              String
+  user                User                @relation(fields: [userId], references: [id], onDelete: Cascade)
+  conversations       Conversation[]
+  knowledgeSources    CharacterKnowledge[]
+  vectorMemories      VectorMemory[]
+
+  @@index([userId])
+  @@index([name])
+}
+
+model CharacterKnowledge {
+  id              String           @id @default(uuid())
+  name            String
+  sourceType      ImportSourceType
+  sourceName      String
+  mimeType        String?
+  fileSize        BigInt?
+  rawContent      String?
+  status          ImportStatus     @default(pending)
+  processingInfo  Json?
+  createdAt       DateTime         @default(now())
+  updatedAt       DateTime         @updatedAt
+
+  characterId     String
+  character       Character        @relation(fields: [characterId], references: [id], onDelete: Cascade)
+  vectorMemories  VectorMemory[]
+
+  @@index([characterId])
+  @@index([status])
+}

apps/backend/prisma/models/conversation.prisma

@@ -0,0 +1,38 @@
+// Conversation and participant models
+
+model Conversation {
+  id             String    @id @default(uuid())
+  title          String?
+  messageCount   Int       @default(0)
+  totalTokens    Int       @default(0)
+  settings       Json      @default("{}")
+  createdAt      DateTime  @default(now())
+  updatedAt      DateTime  @updatedAt
+
+  userId         String
+  user           User                 @relation(fields: [userId], references: [id], onDelete: Cascade)
+  characterId    String
+  character      Character            @relation(fields: [characterId], references: [id], onDelete: Cascade)
+  messages       Message[]
+  vectorMemories VectorMemory[]
+  storyBranches  StoryBranch[]
+  participants   ConversationParticipant[]
+
+  @@index([userId])
+  @@index([characterId])
+  @@index([createdAt])
+}
+
+model ConversationParticipant {
+  id              String    @id @default(uuid())
+  isActive        Boolean   @default(true)
+  autoRespond     Boolean   @default(true)
+  createdAt       DateTime  @default(now())
+
+  conversationId  String
+  conversation    Conversation @relation(fields: [conversationId], references: [id], onDelete: Cascade)
+  characterId     String
+
+  @@unique([conversationId, characterId])
+  @@index([conversationId])
+}

apps/backend/prisma/models/importDocument.prisma

@@ -0,0 +1,21 @@
+// General import documents (not linked to characters)
+
+model ImportDocument {
+  id              String           @id @default(uuid())
+  sourceType      ImportSourceType
+  sourceName      String
+  mimeType        String?
+  fileSize        BigInt?
+  content         String?
+  status          ImportStatus     @default(pending)
+  errorMessage    String?
+  metadata        Json?
+  createdAt       DateTime         @default(now())
+  updatedAt       DateTime         @updatedAt
+
+  userId          String
+  user            User             @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+  @@index([userId])
+  @@index([status])
+}

apps/backend/prisma/models/message.prisma

@@ -0,0 +1,24 @@
+// Message model
+
+enum MessageRole {
+  user
+  assistant
+  system
+}
+
+model Message {
+  id              String      @id @default(uuid())
+  role            MessageRole
+  content         String
+  tokensUsed      Int?
+  model           String?
+  metadata        Json?
+  createdAt       DateTime    @default(now())
+
+  conversationId  String
+  conversation    Conversation @relation(fields: [conversationId], references: [id], onDelete: Cascade)
+
+  @@index([conversationId])
+  @@index([createdAt])
+  @@index([conversationId, createdAt])
+}

apps/backend/prisma/models/storyBranch.prisma

@@ -0,0 +1,21 @@
+// Story branching for narrative generation (Phase 2)
+
+model StoryBranch {
+  id              String    @id @default(uuid())
+  title           String?
+  content         String
+  userDirection   String
+  generationParams Json?
+  depth           Int       @default(0)
+  branchOrder     Int       @default(0)
+  createdAt       DateTime  @default(now())
+
+  conversationId  String
+  conversation    Conversation  @relation(fields: [conversationId], references: [id], onDelete: Cascade)
+  parentId        String?
+  parent          StoryBranch?  @relation("BranchTree", fields: [parentId], references: [id], onDelete: Cascade)
+  children        StoryBranch[] @relation("BranchTree")
+
+  @@index([conversationId])
+  @@index([parentId])
+}

apps/backend/prisma/models/user.prisma

@@ -0,0 +1,25 @@
+// User model and related enums
+
+enum UserRole {
+  USER
+  ADMIN
+}
+
+model User {
+  id            String    @id @default(uuid())
+  email         String    @unique
+  username      String    @unique
+  passwordHash  String?
+  keycloakSub   String?   @unique
+  role          UserRole  @default(USER)
+  isActive      Boolean   @default(true)
+  createdAt     DateTime  @default(now())
+  updatedAt     DateTime  @updatedAt
+
+  characters    Character[]
+  conversations Conversation[]
+  importDocs    ImportDocument[]
+
+  @@index([email])
+  @@index([keycloakSub])
+}

apps/backend/prisma/models/vectorMemory.prisma

@@ -0,0 +1,29 @@
+// Vector memory for embeddings (conversation and character knowledge)
+
+enum MemoryType {
+  conversation
+  character
+}
+
+model VectorMemory {
+  id              String    @id @default(uuid())
+  content         String
+  embedding       Unsupported("vector")?
+  memoryType      MemoryType @default(conversation)
+  metadata        Json?
+  createdAt       DateTime  @default(now())
+
+  conversationId  String?
+  conversation    Conversation? @relation(fields: [conversationId], references: [id], onDelete: Cascade)
+  
+  characterId     String?
+  character       Character?    @relation(fields: [characterId], references: [id], onDelete: Cascade)
+  
+  knowledgeId     String?
+  knowledge       CharacterKnowledge? @relation(fields: [knowledgeId], references: [id], onDelete: Cascade)
+
+  @@index([conversationId])
+  @@index([characterId])
+  @@index([knowledgeId])
+  @@index([memoryType])
+}