feat: 實作 Multi-tenancy 多租戶架構 (stancl/tenancy)

- 安裝並設定 stancl/tenancy 套件
- 分離 Central / Tenant migrations
- 建立 Tenant Model 與資料遷移指令
- 建立房東後台 CRUD (Landlord Dashboard)
- 新增租戶管理頁面 (列表、新增、編輯、詳情)
- 新增域名管理功能
- 更新部署手冊

database/migrations/2019_09_15_000010_create_tenants_table.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class CreateTenantsTable extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up(): void
+    {
+        Schema::create('tenants', function (Blueprint $table) {
+            $table->string('id')->primary();
+
+            // your custom columns may go here
+
+            $table->timestamps();
+            $table->json('data')->nullable();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('tenants');
+    }
+}

database/migrations/2019_09_15_000020_create_domains_table.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+class CreateDomainsTable extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up(): void
+    {
+        Schema::create('domains', function (Blueprint $table) {
+            $table->increments('id');
+            $table->string('domain', 255)->unique();
+            $table->string('tenant_id');
+
+            $table->timestamps();
+            $table->foreign('tenant_id')->references('id')->on('tenants')->onUpdate('cascade')->onDelete('cascade');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('domains');
+    }
+}