feat: add bun-fullstack agent and update skills

.agent/skills/tech-stack/elysiajs/integrations/react-email.md

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+# React Email Integration
+
+## What It Is
+Use React components to create emails. Direct JSX import via Bun.
+
+## Installation
+```bash
+bun add -d react-email
+bun add @react-email/components react react-dom
+```
+
+Script in `package.json`:
+```json
+{
+  "scripts": {
+    "email": "email dev --dir src/emails"
+  }
+}
+```
+
+Email templates → `src/emails` directory.
+
+### TypeScript
+Add to `tsconfig.json`:
+```json
+{
+  "compilerOptions": {
+    "jsx": "react"
+  }
+}
+```
+
+## Email Template
+```tsx
+// src/emails/otp.tsx
+import * as React from 'react'
+import { Tailwind, Section, Text } from '@react-email/components'
+
+export default function OTPEmail({ otp }: { otp: number }) {
+  return (
+    <Tailwind>
+      <Section className="flex justify-center items-center w-full min-h-screen font-sans">
+        <Section className="flex flex-col items-center w-76 rounded-2xl px-6 py-1 bg-gray-50">
+          <Text className="text-xs font-medium text-violet-500">
+            Verify your Email Address
+          </Text>
+          <Text className="text-gray-500 my-0">
+            Use the following code to verify your email address
+          </Text>
+          <Text className="text-5xl font-bold pt-2">{otp}</Text>
+          <Text className="text-gray-400 font-light text-xs pb-4">
+            This code is valid for 10 minutes
+          </Text>
+          <Text className="text-gray-600 text-xs">
+            Thank you for joining us
+          </Text>
+        </Section>
+      </Section>
+    </Tailwind>
+  )
+}
+
+OTPEmail.PreviewProps = { otp: 123456 }
+```
+
+`@react-email/components` → email-client compatible (Gmail, Outlook). Tailwind support.
+
+`PreviewProps` → playground only.
+
+## Preview
+```bash
+bun email
+```
+
+Opens browser with preview.
+
+## Send Email
+Render with `react-dom/server`, submit via provider:
+
+### Nodemailer
+```typescript
+import { renderToStaticMarkup } from 'react-dom/server'
+import OTPEmail from './emails/otp'
+import nodemailer from 'nodemailer'
+
+const transporter = nodemailer.createTransport({
+  host: 'smtp.gehenna.sh',
+  port: 465,
+  auth: { user: 'makoto', pass: '12345678' }
+})
+
+.get('/otp', async ({ body }) => {
+  const otp = ~~(Math.random() * 900_000) + 100_000
+  const html = renderToStaticMarkup(<OTPEmail otp={otp} />)
+  
+  await transporter.sendMail({
+    from: '[email protected]',
+    to: body,
+    subject: 'Verify your email address',
+    html
+  })
+  
+  return { success: true }
+}, {
+  body: t.String({ format: 'email' })
+})
+```
+
+### Resend
+```typescript
+import OTPEmail from './emails/otp'
+import Resend from 'resend'
+
+const resend = new Resend('re_123456789')
+
+.get('/otp', ({ body }) => {
+  const otp = ~~(Math.random() * 900_000) + 100_000
+  
+  await resend.emails.send({
+    from: '[email protected]',
+    to: body,
+    subject: 'Verify your email address',
+    html: <OTPEmail otp={otp} />  // Direct JSX
+  })
+  
+  return { success: true }
+})
+```
+
+Direct JSX import thanks to Bun.
+
+Other providers: AWS SES, SendGrid.
+
+See [React Email Integrations](https://react.email/docs/integrations/overview).