feat(auth): add username field to user schema and authentication process

- Updated user schema to include a unique username field.
- Modified authentication logic to support sign-in using either email or username.
- Enhanced sign-up process to require a username and validate its uniqueness.
- Updated login and profile routes to reflect changes in user identification.
- Adjusted frontend forms to accommodate username input alongside email.

src/lib/server/auth.ts

@@ -9,6 +9,15 @@ export const auth = betterAuth({
 	baseURL: env.ORIGIN,
 	secret: env.BETTER_AUTH_SECRET || 'secret',
 	database: drizzleAdapter(db, { provider: 'sqlite' }),
+	user: {
+		additionalFields: {
+			username: {
+				type: 'string',
+				required: true,
+				unique: true
+			}
+		}
+	},
 	emailAndPassword: { enabled: true },
 	plugins: [sveltekitCookies(getRequestEvent)] // make sure this is the last plugin in the array
 });

src/lib/server/db/auth.schema.ts

@@ -4,6 +4,7 @@ import { sqliteTable, text, integer, index } from "drizzle-orm/sqlite-core";
 export const user = sqliteTable("user", {
   id: text("id").primaryKey(),
   name: text("name").notNull(),
+  username: text("username").notNull().unique(),
   email: text("email").notNull().unique(),
   emailVerified: integer("email_verified", { mode: "boolean" })
     .default(false)