Migrate from Resend

# Before
npm install resend

# After
npm install send0

# Before
pip install resend

# After
pip install send0

// Before (Resend)
import { Resend } from 'resend';
const resend = new Resend('re_...');

// After (send0)
import { Send0 } from 'send0';
const send0 = new Send0('sk_live_...');

# Before (Resend)
import resend
resend.api_key = "re_..."

# After (send0)
from send0 import Send0
client = Send0("sk_live_...")

// Before (Resend)
const email = await resend.emails.send({
  from: 'hello@acme.com',
  to: 'user@example.com',
  subject: 'Welcome!',
  html: '<p>Hello</p>',
  tags: [{ name: 'category', value: 'onboarding' }],
});

// After (send0)
const email = await send0.emails.send({
  from: 'hello@acme.com',
  to: 'user@example.com',
  subject: 'Welcome!',
  html: '<p>Hello</p>',
  tags: { category: 'onboarding' },
});

# Before (Resend)
email = resend.Emails.send({
    "from": "hello@acme.com",
    "to": "user@example.com",
    "subject": "Welcome!",
    "html": "<p>Hello</p>",
})

# After (send0)
email = client.emails.send(
    from_address="hello@acme.com",
    to="user@example.com",
    subject="Welcome!",
    html="<p>Hello</p>",
)

// Before (Resend) — uses Svix
import { Webhook } from 'svix';
const wh = new Webhook(secret);
const event = wh.verify(body, headers);

// After (send0) — built-in
import { Send0 } from 'send0';
const event = Send0.webhooks.verify(body, headers, secret);

# After (send0)
from send0 import Webhooks
event = Webhooks.verify(body, headers, secret)

// Add domain
const domain = await send0.domains.create({ domain: 'mail.acme.com' });

// Configure DNS records from domain.dns_records
// Then verify
const result = await send0.domains.verify(domain.id);