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>

package.json

@@ -67,6 +67,7 @@
     "negotiator": "^1.0.0",
     "next": "^15.5.3",
     "next-intl": "^4.3.9",
+    "nodemailer": "^7.0.9",
     "openai": "^5.22.0",
     "pdf-parse": "^1.1.1",
     "pg": "^8.16.3",
@@ -92,6 +93,7 @@
   "devDependencies": {
     "@types/bcryptjs": "^2.4.6",
     "@types/jsonwebtoken": "^9.0.10",
+    "@types/nodemailer": "^7.0.2",
     "ignore-loader": "^0.1.2",
     "tsx": "^4.20.5"
   }