added user signup feature

internal/model/book.go

@@ -4,7 +4,7 @@ import "gorm.io/gorm"
 
 type Book struct {
 	gorm.Model
-	Title  string `json:"title"`
+	Title  string `json:"title" gorm:"not null"`
 	Author string `json:"author"`
-	Rating int `json:"rating"`
+	Rating int    `json:"rating"`
 }

internal/model/user.go

@@ -0,0 +1,9 @@
+package model
+
+import "gorm.io/gorm"
+
+type User struct {
+	gorm.Model
+	Name     string `gorm:"index;uniqueIndex"`
+	Password string
+}