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/app/Enums/IdentityMatchConfidence.php

@@ -6,6 +6,14 @@ namespace App\Enums;
 
 enum IdentityMatchConfidence: string
 {
-    case EXACT = 'exact';
-    case FUZZY = 'fuzzy';
+    case HIGH = 'high';
+    case MEDIUM = 'medium';
+
+    public function label(): string
+    {
+        return match ($this) {
+            self::HIGH => 'Hoge zekerheid',
+            self::MEDIUM => 'Gemiddelde zekerheid',
+        };
+    }
 }