Implement expense tracking foundation for v1

prisma/schema.prisma

@@ -0,0 +1,45 @@
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "sqlite"
+  url      = env("DATABASE_URL")
+}
+
+enum Category {
+  RENT
+  FOOD
+  TRANSPORT
+  BILLS
+  SHOPPING
+  HEALTH
+  ENTERTAINMENT
+  MISC
+}
+
+model Expense {
+  id          String   @id @default(cuid())
+  date        String
+  title       String
+  amountCents Int
+  category    Category
+  createdAt   DateTime @default(now())
+}
+
+model Paycheck {
+  id          String   @id @default(cuid())
+  payDate     String
+  amountCents Int
+  createdAt   DateTime @default(now())
+}
+
+model MonthlyInsight {
+  id              String   @id @default(cuid())
+  month           String
+  year            Int
+  generatedAt     DateTime @default(now())
+  summary         String
+  recommendations String
+  inputSnapshot   String
+}