feat: complete person identity matching system with fuzzy detection, revert, and manual link

Implements the full identity matching engine: email matching (HIGH confidence),
fuzzy name matching with Levenshtein distance (MEDIUM confidence, upgradable to
HIGH with DOB tiebreaker), manual link/unlink, revert confirmed matches, and
automatic detection via PersonObserver. Includes 33 comprehensive tests, frontend
integration with confirm/dismiss/unlink UI, and match indicators in the persons list.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/database/factories/UserFactory.php

@@ -20,6 +20,7 @@ final class UserFactory extends Factory
         return [
             'first_name' => fake('nl_NL')->firstName(),
             'last_name' => fake('nl_NL')->lastName(),
+            'date_of_birth' => fake()->dateTimeBetween('-50 years', '-18 years')->format('Y-m-d'),
             'email' => fake()->unique()->safeEmail(),
             'email_verified_at' => now(),
             'password' => static::$password ??= Hash::make('password'),