fix: switch contact form to use local SMTP (Maddy) instead of Mailgun

Changed contact form email delivery to use local Maddy SMTP server for better reliability.

**Changes:**
- Created new SMTP service (lib/smtp.ts) using nodemailer
- Configured to use localhost:25 (Maddy SMTP)
- Updated contact API to use smtpService instead of mailgunService
- Installed nodemailer and @types/nodemailer

**Benefits:**
- Simpler configuration (no external API dependencies)
- Local email delivery (more reliable for internal emails)
- No API rate limits or authentication issues
- Direct delivery to contact@biblical-guide.com

**Roundcube still uses Mailgun SMTP** for outgoing emails from webmail interface.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/api/contact/route.ts

@@ -1,5 +1,5 @@
 import { NextRequest, NextResponse } from 'next/server'
-import { mailgunService } from '@/lib/mailgun'
+import { smtpService } from '@/lib/smtp'
 import { z } from 'zod'
 
 export const runtime = 'nodejs'
@@ -46,8 +46,8 @@ export async function POST(request: NextRequest) {
       }, { status: 400 })
     }
 
-    // Send email using Mailgun
-    const emailResult = await mailgunService.sendContactForm({
+    // Send email using local SMTP server (Maddy)
+    const emailResult = await smtpService.sendContactForm({
       name,
       email,
       subject,