feat(user): add bio and custom links functionality

prisma/migrations/20260127100000_add_user_bio_and_custom_links/migration.sql

@@ -0,0 +1,3 @@
+-- AlterTable
+ALTER TABLE "users" ADD COLUMN "bio" VARCHAR(250);
+ALTER TABLE "users" ADD COLUMN "customLinks" JSONB;

prisma/schema.prisma

@@ -15,6 +15,8 @@ model User {
   name                      String?
   password                  String?
   avatar                    String?
+  bio                       String?                @db.VarChar(250)
+  customLinks               Json?                  // Array of {type: string, url: string, label?: string}
   role                      UserRole               @default(USER)
   locale                    String                 @default("en")
   emailVerified             DateTime?