feat: person identity matching with detection, confirmation and audit trail

Implements enterprise-grade identity resolution (detect → suggest → confirm)
for Person ↔ User linking. Matches are detected automatically on person
creation and user account creation, then surfaced to organisers for explicit
confirmation or dismissal. No silent auto-linking.

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

api/database/factories/PersonIdentityMatchFactory.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Database\Factories;
+
+use App\Enums\IdentityMatchConfidence;
+use App\Enums\IdentityMatchMethod;
+use App\Enums\IdentityMatchStatus;
+use App\Models\Person;
+use App\Models\PersonIdentityMatch;
+use App\Models\User;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/** @extends Factory<PersonIdentityMatch> */
+final class PersonIdentityMatchFactory extends Factory
+{
+    protected $model = PersonIdentityMatch::class;
+
+    /** @return array<string, mixed> */
+    public function definition(): array
+    {
+        return [
+            'person_id' => Person::factory(),
+            'matched_user_id' => User::factory(),
+            'matched_on' => IdentityMatchMethod::EMAIL,
+            'confidence' => IdentityMatchConfidence::EXACT,
+            'status' => IdentityMatchStatus::PENDING,
+            'resolved_by_user_id' => null,
+            'resolved_at' => null,
+        ];
+    }
+
+    public function confirmed(): static
+    {
+        return $this->state(fn () => [
+            'status' => IdentityMatchStatus::CONFIRMED,
+            'resolved_by_user_id' => User::factory(),
+            'resolved_at' => now(),
+        ]);
+    }
+
+    public function dismissed(): static
+    {
+        return $this->state(fn () => [
+            'status' => IdentityMatchStatus::DISMISSED,
+            'resolved_by_user_id' => User::factory(),
+            'resolved_at' => now(),
+        ]);
+    }
+}