refactor: migrate project from Flask to Next.js with TypeScript, Prisma, and Edge TTS integration

prisma/schema.prisma

@@ -0,0 +1,38 @@
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "sqlite"
+  url      = "file:./dev.db"
+}
+
+model Episode {
+  id              String      @id @default(cuid())
+  title           String
+  originalContent String
+  scriptContent   String?
+  mode            String      @default("VERBATIM") // VERBATIM | FEYNMAN | DUAL_HOST
+  status          String      @default("PENDING")  // PENDING | PROCESSING | READY | FAILED
+  errorMessage    String?
+  durationSeconds Float?
+  audioUrl        String?
+  timingsJson     String?     // Serialized array of cues / timestamps [{text, startTime, endTime, speaker}]
+  
+  stages          StageItem[]
+  createdAt       DateTime    @default(now())
+  updatedAt       DateTime    @updatedAt
+}
+
+model StageItem {
+  id               String   @id @default(cuid())
+  episodeId        String
+  timestampSeconds Float
+  type             String   // IMAGE | CODE | CALLOUT
+  title            String?
+  content          String   // Image URL, Code snippet, or Callout text
+  caption          String?
+  
+  episode          Episode  @relation(fields: [episodeId], references: [id], onDelete: Cascade)
+  createdAt        DateTime @default(now())
+}