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/app/Http/Resources/Api/V1/PersonResource.php

@@ -24,6 +24,23 @@ final class PersonResource extends JsonResource
             'created_at' => $this->created_at->toIso8601String(),
             'crowd_type' => new CrowdTypeResource($this->whenLoaded('crowdType')),
             'company' => new CompanyResource($this->whenLoaded('company')),
+            'pending_identity_match' => $this->when(
+                $this->relationLoaded('pendingIdentityMatch') && $this->pendingIdentityMatch,
+                function () {
+                    $match = $this->pendingIdentityMatch;
+
+                    return [
+                        'match_id' => $match->id,
+                        'matched_user' => [
+                            'id' => $match->matchedUser->id,
+                            'name' => $match->matchedUser->name,
+                            'email' => $match->matchedUser->email,
+                        ],
+                        'matched_on' => $match->matched_on->value,
+                        'confidence' => $match->confidence->value,
+                    ];
+                }
+            ),
             'tags' => $this->when(
                 $this->user_id && $this->relationLoaded('user'),
                 function () {