feat: implement database schema with Prisma ORM

Add PostgreSQL schema with 8 models (User, Session, McpServer, McpProfile,
Project, ProjectMcpProfile, McpInstance, AuditLog), comprehensive model
tests (31 passing), seed data for default MCP servers, and package exports.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/db/prisma/schema.prisma

@@ -0,0 +1,172 @@
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "postgresql"
+  url      = env("DATABASE_URL")
+}
+
+// ── Users ──
+
+model User {
+  id        String   @id @default(cuid())
+  email     String   @unique
+  name      String?
+  role      Role     @default(USER)
+  version   Int      @default(1)
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  sessions  Session[]
+  auditLogs AuditLog[]
+  projects  Project[]
+
+  @@index([email])
+}
+
+enum Role {
+  USER
+  ADMIN
+}
+
+// ── Sessions ──
+
+model Session {
+  id        String   @id @default(cuid())
+  token     String   @unique
+  userId    String
+  expiresAt DateTime
+  createdAt DateTime @default(now())
+
+  user User @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+  @@index([token])
+  @@index([userId])
+  @@index([expiresAt])
+}
+
+// ── MCP Servers ──
+
+model McpServer {
+  id            String          @id @default(cuid())
+  name          String          @unique
+  description   String          @default("")
+  packageName   String?
+  dockerImage   String?
+  transport     Transport       @default(STDIO)
+  repositoryUrl String?
+  envTemplate   Json            @default("[]")
+  version       Int             @default(1)
+  createdAt     DateTime        @default(now())
+  updatedAt     DateTime        @updatedAt
+
+  profiles  McpProfile[]
+  instances McpInstance[]
+
+  @@index([name])
+}
+
+enum Transport {
+  STDIO
+  SSE
+  STREAMABLE_HTTP
+}
+
+// ── MCP Profiles ──
+
+model McpProfile {
+  id          String   @id @default(cuid())
+  name        String
+  serverId    String
+  permissions Json     @default("[]")
+  envOverrides Json    @default("{}")
+  version     Int      @default(1)
+  createdAt   DateTime @default(now())
+  updatedAt   DateTime @updatedAt
+
+  server   McpServer            @relation(fields: [serverId], references: [id], onDelete: Cascade)
+  projects ProjectMcpProfile[]
+
+  @@unique([name, serverId])
+  @@index([serverId])
+}
+
+// ── Projects ──
+
+model Project {
+  id          String   @id @default(cuid())
+  name        String   @unique
+  description String   @default("")
+  ownerId     String
+  version     Int      @default(1)
+  createdAt   DateTime @default(now())
+  updatedAt   DateTime @updatedAt
+
+  owner    User                 @relation(fields: [ownerId], references: [id], onDelete: Cascade)
+  profiles ProjectMcpProfile[]
+
+  @@index([name])
+  @@index([ownerId])
+}
+
+// ── Project <-> Profile join table ──
+
+model ProjectMcpProfile {
+  id        String @id @default(cuid())
+  projectId String
+  profileId String
+
+  project Project    @relation(fields: [projectId], references: [id], onDelete: Cascade)
+  profile McpProfile @relation(fields: [profileId], references: [id], onDelete: Cascade)
+
+  @@unique([projectId, profileId])
+  @@index([projectId])
+  @@index([profileId])
+}
+
+// ── MCP Instances (running containers) ──
+
+model McpInstance {
+  id          String         @id @default(cuid())
+  serverId    String
+  containerId String?
+  status      InstanceStatus @default(STOPPED)
+  port        Int?
+  metadata    Json           @default("{}")
+  version     Int            @default(1)
+  createdAt   DateTime       @default(now())
+  updatedAt   DateTime       @updatedAt
+
+  server McpServer @relation(fields: [serverId], references: [id], onDelete: Cascade)
+
+  @@index([serverId])
+  @@index([status])
+}
+
+enum InstanceStatus {
+  STARTING
+  RUNNING
+  STOPPING
+  STOPPED
+  ERROR
+}
+
+// ── Audit Logs ──
+
+model AuditLog {
+  id        String   @id @default(cuid())
+  userId    String
+  action    String
+  resource  String
+  resourceId String?
+  details   Json     @default("{}")
+  createdAt DateTime @default(now())
+
+  user User @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+  @@index([userId])
+  @@index([action])
+  @@index([resource])
+  @@index([createdAt])
+}