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/migrations/2026_04_14_200000_add_date_of_birth_to_users_table.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->date('date_of_birth')->nullable()->after('last_name');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('users', function (Blueprint $table) {
+            $table->dropColumn('date_of_birth');
+        });
+    }
+};

api/database/migrations/2026_04_14_200001_enhance_person_identity_matches_table.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('person_identity_matches', function (Blueprint $table) {
+            $table->json('match_details')->nullable()->after('status');
+
+            $table->foreignUlid('confirmed_by_user_id')
+                ->nullable()
+                ->after('match_details')
+                ->constrained('users')
+                ->nullOnDelete();
+
+            $table->timestamp('confirmed_at')->nullable()->after('confirmed_by_user_id');
+
+            $table->foreignUlid('dismissed_by_user_id')
+                ->nullable()
+                ->after('confirmed_at')
+                ->constrained('users')
+                ->nullOnDelete();
+
+            $table->timestamp('dismissed_at')->nullable()->after('dismissed_by_user_id');
+
+            $table->foreignUlid('reverted_by_user_id')
+                ->nullable()
+                ->after('dismissed_at')
+                ->constrained('users')
+                ->nullOnDelete();
+
+            $table->timestamp('reverted_at')->nullable()->after('reverted_by_user_id');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('person_identity_matches', function (Blueprint $table) {
+            $table->dropForeign(['confirmed_by_user_id']);
+            $table->dropForeign(['dismissed_by_user_id']);
+            $table->dropForeign(['reverted_by_user_id']);
+            $table->dropColumn([
+                'match_details',
+                'confirmed_by_user_id',
+                'confirmed_at',
+                'dismissed_by_user_id',
+                'dismissed_at',
+                'reverted_by_user_id',
+                'reverted_at',
+            ]);
+        });
+    }
+};