Implement email functionality and improve booking system

Features:
- Add real email sending with PHP mail() function
- Create HTML email templates for bookings
- Send booking notifications to bands
- Send confirmation emails to customers
- Add email field to bands table and profile
- Enable guest bookings without login
- Improve form validation and UX
- Add migration script for database updates

This fixes the non-working email system and improves the reservation/booking process significantly.

migrate_add_band_email.php

@@ -0,0 +1,35 @@
+<?php
+/**
+ * Migration: Add email column to bands table
+ * Run this once to update existing databases
+ */
+
+require_once __DIR__ . '/includes/database.php';
+
+try {
+    $pdo = db();
+
+    $columns = $pdo->query("PRAGMA table_info(bands)")->fetchAll(PDO::FETCH_ASSOC);
+    $hasEmail = false;
+
+    foreach ($columns as $column) {
+        if ($column['name'] === 'email') {
+            $hasEmail = true;
+            break;
+        }
+    }
+
+    if (!$hasEmail) {
+        echo "Adding email column to bands table...\n";
+        $pdo->exec("ALTER TABLE bands ADD COLUMN email TEXT");
+        echo "✓ Email column added successfully!\n";
+    } else {
+        echo "✓ Email column already exists.\n";
+    }
+
+    echo "\nMigration completed successfully!\n";
+
+} catch (PDOException $e) {
+    echo "Error: " . $e->getMessage() . "\n";
+    exit(1);
+}