Add forgot-password and reset-password flow

Users can now request a password reset link via email. Better Auth
sendResetPassword callback sends a branded email via Resend. Login
page shows success notice after password is set.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/auth.ts

@@ -3,7 +3,7 @@ import { prismaAdapter } from "better-auth/adapters/prisma";
 import { admin } from "better-auth/plugins";
 import { prisma } from "./prisma";
 import bcrypt from "bcryptjs";
-import { sendWelcomeEmail } from "./email";
+import { sendWelcomeEmail, sendPasswordResetEmail } from "./email";
 
 export const auth = betterAuth({
   database: prismaAdapter(prisma, {
@@ -16,6 +16,9 @@ export const auth = betterAuth({
       hash: (password) => bcrypt.hash(password, 10),
       verify: ({ hash, password }) => bcrypt.compare(password, hash),
     },
+    sendResetPassword: async ({ user, url }) => {
+      await sendPasswordResetEmail(user.email, user.name, url);
+    },
   },
   databaseHooks: {
     user: {