Refactor year management in the database layer, enhance Year model with budget field, and update UI components for year selection and dashboard display

prisma/schema.prisma

@@ -10,7 +10,8 @@ datasource db {
 }
 
 model Year {
-  year Int @id
+  year   Int   @id
+  budget Float @default(3000)
 
   people Person[]
 }