feat(api): add findings module with vector search (MS22-DB-001, MS22-API-001)

apps/api/prisma/schema.prisma

@@ -298,6 +298,7 @@ model Workspace {
   agents                       Agent[]
   agentSessions                AgentSession[]
   agentTasks                   AgentTask[]
+  findings                     Finding[]
   userLayouts                  UserLayout[]
   knowledgeEntries             KnowledgeEntry[]
   knowledgeTags                KnowledgeTag[]
@@ -689,6 +690,7 @@ model AgentTask {
   createdBy   User        @relation("AgentTaskCreator", fields: [createdById], references: [id], onDelete: Cascade)
   createdById String      @map("created_by_id") @db.Uuid
   runnerJobs  RunnerJob[]
+  findings    Finding[]
 
   @@unique([id, workspaceId])
   @@index([workspaceId])
@@ -698,6 +700,33 @@ model AgentTask {
   @@map("agent_tasks")
 }
 
+model Finding {
+  id          String  @id @default(uuid()) @db.Uuid
+  workspaceId String  @map("workspace_id") @db.Uuid
+  taskId      String? @map("task_id") @db.Uuid
+
+  agentId String @map("agent_id")
+  type    String
+  title   String
+  data    Json
+  summary String @db.Text
+  // Note: vector dimension (1536) must match EMBEDDING_DIMENSION constant in @mosaic/shared
+  embedding Unsupported("vector(1536)")?
+
+  createdAt DateTime @default(now()) @map("created_at") @db.Timestamptz
+  updatedAt DateTime @updatedAt @map("updated_at") @db.Timestamptz
+
+  workspace Workspace @relation(fields: [workspaceId], references: [id], onDelete: Cascade)
+  task      AgentTask? @relation(fields: [taskId], references: [id], onDelete: SetNull)
+
+  @@unique([id, workspaceId])
+  @@index([workspaceId])
+  @@index([agentId])
+  @@index([type])
+  @@index([taskId])
+  @@map("findings")
+}
+
 model AgentSession {
   id          String  @id @default(uuid()) @db.Uuid
   workspaceId String  @map("workspace_id") @db.Uuid