fix(api-tokens): persist expiration warning state

Track when expiration warnings are sent on personal access tokens so repeated job runs or cache flushes do not send duplicate notifications.

database/migrations/2026_05_13_000000_add_expiration_warning_sent_at_to_personal_access_tokens_table.php

@@ -0,0 +1,30 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('personal_access_tokens', function (Blueprint $table) {
+            $table->timestamp('api_token_expiration_warning_sent_at')->nullable()->after('expires_at');
+            $table->index(['expires_at', 'api_token_expiration_warning_sent_at'], 'personal_access_tokens_expiration_warning_index');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('personal_access_tokens', function (Blueprint $table) {
+            $table->dropIndex('personal_access_tokens_expiration_warning_index');
+            $table->dropColumn('api_token_expiration_warning_sent_at');
+        });
+    }
+};