feat: kb both volumes

prisma/schema.prisma

@@ -63,6 +63,36 @@ model BookMeta {
   @@map("book_meta")
 }
 
+// ---------------------------------------------------------------------------
+// ProseChapter — for prose books like Kṛṣṇa Book (no verse structure)
+//
+// book: "kb"
+// volume: volume number (1 or 2 for KB)
+// chapter: chapter number within the volume
+// title: chapter title
+// type: "chapter" | "intro-segment"
+// slug: URL-friendly identifier (e.g. "01", "preface", "words-from-apple")
+// order: sort order (chapter number for chapters, custom for intro segments)
+// paragraphs: array of HTML paragraph strings
+// ---------------------------------------------------------------------------
+model ProseChapter {
+  id         String   @id @default(auto()) @map("_id") @db.ObjectId
+  book       String   // "kb"
+  volume     Int
+  chapter    Int?     // null for intro segments
+  title      String
+  type       String   // "chapter" | "intro-segment"
+  slug       String
+  order      Int
+  paragraphs String[]
+
+  @@unique([book, volume, slug])
+  @@index([book])
+  @@index([book, volume])
+  @@index([book, volume, type])
+  @@map("prose_chapters")
+}
+
 // ---------------------------------------------------------------------------
 // GlossaryEntry — individual glossary term + definition
 // ---------------------------------------------------------------------------