Refactor user and session migrations to use UUIDs; update DatabaseSeeder for test user creation; enhance LetterController with search functionality and API route protection

database/migrations/0001_01_01_000000_create_users_table.php

@@ -12,7 +12,7 @@ return new class extends Migration
     public function up(): void
     {
         Schema::create('users', function (Blueprint $table) {
-            $table->id();
+            $table->uuid('id')->primary();
             $table->string('name');
             $table->string('email')->unique();
             $table->timestamp('email_verified_at')->nullable();
@@ -29,7 +29,8 @@ return new class extends Migration
 
         Schema::create('sessions', function (Blueprint $table) {
             $table->string('id')->primary();
-            $table->foreignId('user_id')->nullable()->index();
+            $table->uuid('user_id')->nullable()->index();
+            $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
             $table->string('ip_address', 45)->nullable();
             $table->text('user_agent')->nullable();
             $table->longText('payload');

database/migrations/2025_03_08_140737_create_personal_access_tokens_table.php

@@ -13,7 +13,7 @@ return new class extends Migration
     {
         Schema::create('personal_access_tokens', function (Blueprint $table) {
             $table->id();
-            $table->morphs('tokenable');
+            $table->uuidMorphs('tokenable');
             $table->string('name');
             $table->string('token', 64)->unique();
             $table->text('abilities')->nullable();