Add stage 7: email verification magic links and a profile page

Backend
- New Mail namespace: a Mailer interface with SMTP (phpmailer), PHP mail()
  (the default fallback), and log-to-file transports, selected by
  MAIL_TRANSPORT. EmailVerifier issues a hashed, 15-minute magic-link token
  and sends the link (APP_URL/verify-email?token=...).
- Migration 005: email_verifications table + users.verification_email_sent_at.
- Registration now emails a verification link (best effort — a send failure
  doesn't fail registration).
- POST /api/auth/verify-email consumes a token and returns a session, so
  opening the link verifies the address (or applies a pending email change)
  and logs the user in. Single-use; distinct 400s for invalid/used/expired.
- POST /api/email/verification resends; POST /api/email/change requests a
  deferred change (current password required; link goes to the new address;
  users.email only updates when that link is opened). Both throttled to once
  per 60s, returning 429 + retry_after.
- GET /api/me and every session payload now include pending_email. Shared
  SessionPayload builds the user/session JSON for all entry points.

Frontend
- /verify-email view: posts the token, adopts the returned session, redirects.
- /profile view: shows address + status, a resend button with a live cooldown
  (driven by retry_after / 429), and a change-email form (new address +
  current password) that surfaces the pending change.
- Header shows a "verify email" badge linking to the profile.

Tests: 9 new (EmailVerificationTest) covering the link lifecycle, throttle,
and deferred change; AuthTest folded into ApiTestCase, which now routes mail
to a per-test log. Suite: 32 passing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/Repository/UserRepository.php

@@ -9,7 +9,7 @@ use PDO;
 /**
  * Data access for the `users` table. Rows are returned as associative arrays.
  *
- * @phpstan-type UserRow array{id: int, email: string, password_hash: string, email_verified_at: string|null, created_at: string, updated_at: string}
+ * @phpstan-type UserRow array{id: int, email: string, password_hash: string, email_verified_at: string|null, verification_email_sent_at: string|null, created_at: string, updated_at: string}
  */
 final class UserRepository
 {
@@ -62,6 +62,35 @@ final class UserRepository
         return $user;
     }
 
+    public function markEmailVerified(int $id): void
+    {
+        $this->pdo->prepare(
+            "UPDATE users SET email_verified_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now'),
+                    updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now')
+             WHERE id = :id"
+        )->execute(['id' => $id]);
+    }
+
+    /**
+     * Apply a confirmed email change: set the address and mark it verified.
+     */
+    public function updateEmail(int $id, string $email): void
+    {
+        $this->pdo->prepare(
+            "UPDATE users SET email = :email,
+                    email_verified_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now'),
+                    updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now')
+             WHERE id = :id"
+        )->execute(['email' => $email, 'id' => $id]);
+    }
+
+    public function markVerificationEmailSent(int $id): void
+    {
+        $this->pdo->prepare(
+            "UPDATE users SET verification_email_sent_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now') WHERE id = :id"
+        )->execute(['id' => $id]);
+    }
+
     /**
      * @param array<string, mixed> $row
      * @return UserRow