feat: add Go, PHP, and Laravel SDKs

- Go SDK: zero deps, functional options pattern, full endpoint coverage
- PHP SDK: PHP 8.1+, curl-based, PdfOptions class, PSR-4 autoloading
- Laravel package: ServiceProvider, Facade, config publishing
- All SDKs document complete PDF options including new v0.4.5 params

sdk/laravel/src/DocFastServiceProvider.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DocFast\Laravel;
+
+use DocFast\Client;
+use Illuminate\Support\ServiceProvider;
+
+class DocFastServiceProvider extends ServiceProvider
+{
+    public function register(): void
+    {
+        $this->mergeConfigFrom(__DIR__ . '/../config/docfast.php', 'docfast');
+
+        $this->app->singleton(Client::class, function ($app) {
+            $config = $app['config']['docfast'];
+            return new Client(
+                $config['api_key'] ?? '',
+                $config['base_url'] ?? 'https://docfast.dev',
+                $config['timeout'] ?? 60,
+            );
+        });
+
+        $this->app->alias(Client::class, 'docfast');
+    }
+
+    public function boot(): void
+    {
+        $this->publishes([
+            __DIR__ . '/../config/docfast.php' => config_path('docfast.php'),
+        ], 'docfast-config');
+    }
+}