feat: Add photo management features, duplicate detection, attempt limits, and admin deletion

- Add duplicate photo detection (file hash and URL checking)
- Add max attempts per photo with UI counter
- Simplify penalty system (auto-enable when points > 0)
- Prevent scores from going below 0
- Add admin photo deletion functionality
- Improve navigation with always-visible logout
- Prevent users from guessing their own photos

lib/email.ts

@@ -0,0 +1,113 @@
+import nodemailer from "nodemailer"
+
+let transporter: nodemailer.Transporter | null = null
+
+async function getTransporter() {
+  if (transporter) return transporter
+
+  // In development, use Ethereal or console transport
+  if (process.env.NODE_ENV === "development") {
+    // Try to use Ethereal for testing
+    try {
+      const testAccount = await nodemailer.createTestAccount()
+      transporter = nodemailer.createTransport({
+        host: "smtp.ethereal.email",
+        port: 587,
+        secure: false,
+        auth: {
+          user: testAccount.user,
+          pass: testAccount.pass,
+        },
+      })
+      return transporter
+    } catch {
+      // Fallback to console transport
+      transporter = nodemailer.createTransport({
+        streamTransport: true,
+        newline: "unix",
+        buffer: true,
+      })
+      return transporter
+    }
+  }
+
+  // Production: use SMTP
+  transporter = nodemailer.createTransport({
+    host: process.env.SMTP_HOST,
+    port: parseInt(process.env.SMTP_PORT || "587"),
+    secure: process.env.SMTP_PORT === "465",
+    auth: {
+      user: process.env.SMTP_USER,
+      pass: process.env.SMTP_PASSWORD,
+    },
+  })
+
+  return transporter
+}
+
+export async function sendNewPhotoEmail(
+  recipientEmail: string,
+  recipientName: string,
+  photoId: string,
+  uploaderName: string
+) {
+  const emailTransporter = await getTransporter()
+  const baseUrl = process.env.NEXTAUTH_URL || "http://localhost:3000"
+  const photoUrl = `${baseUrl}/photos/${photoId}`
+
+  const mailOptions = {
+    from: process.env.SMTP_FROM || "MirrorMatch <noreply@mirrormatch.com>",
+    to: recipientEmail,
+    subject: "New Photo Ready to Guess!",
+    html: `
+      <!DOCTYPE html>
+      <html>
+        <head>
+          <meta charset="utf-8">
+          <meta name="viewport" content="width=device-width, initial-scale=1.0">
+        </head>
+        <body style="font-family: Arial, sans-serif; line-height: 1.6; color: #333; max-width: 600px; margin: 0 auto; padding: 20px;">
+          <div style="background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); padding: 30px; text-align: center; border-radius: 10px 10px 0 0;">
+            <h1 style="color: white; margin: 0;">MirrorMatch</h1>
+          </div>
+          <div style="background: #f9f9f9; padding: 30px; border-radius: 0 0 10px 10px;">
+            <h2 style="color: #667eea; margin-top: 0;">New Photo Uploaded!</h2>
+            <p>Hi ${recipientName},</p>
+            <p><strong>${uploaderName}</strong> has uploaded a new photo for you to guess!</p>
+            <p style="margin: 30px 0;">
+              <a href="${photoUrl}" style="background: #667eea; color: white; padding: 12px 30px; text-decoration: none; border-radius: 5px; display: inline-block;">View Photo & Guess</a>
+            </p>
+            <p style="color: #666; font-size: 14px; margin-top: 30px;">
+              Good luck! 🎯
+            </p>
+          </div>
+        </body>
+      </html>
+    `,
+    text: `
+Hi ${recipientName},
+
+${uploaderName} has uploaded a new photo for you to guess!
+
+View the photo and submit your guess here: ${photoUrl}
+
+Good luck!
+    `.trim(),
+  }
+
+  try {
+    const info = await emailTransporter.sendMail(mailOptions)
+    
+    if (process.env.NODE_ENV === "development") {
+      console.log("Email sent (dev mode):")
+      console.log("Preview URL:", nodemailer.getTestMessageUrl(info) || "Check console")
+      console.log("To:", recipientEmail)
+      console.log("Subject:", mailOptions.subject)
+    }
+    
+    return info
+  } catch (error) {
+    console.error("Error sending email:", error)
+    throw error
+  }
+}