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/php/src/PdfOptions.php

@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DocFast;
+
+/**
+ * PDF generation options.
+ */
+class PdfOptions
+{
+    /** Page size: A4, Letter, Legal, A3, A5, Tabloid. Ignored if width/height set. */
+    public ?string $format = null;
+
+    /** Landscape orientation. */
+    public ?bool $landscape = null;
+
+    /** Page margins using CSS units (e.g. "20mm"). */
+    public ?array $margin = null;
+
+    /** Print background graphics and colors. */
+    public ?bool $printBackground = null;
+
+    /** Suggested filename for the PDF download. */
+    public ?string $filename = null;
+
+    /** HTML template for page header. Requires displayHeaderFooter: true. */
+    public ?string $headerTemplate = null;
+
+    /** HTML template for page footer. */
+    public ?string $footerTemplate = null;
+
+    /** Show header and footer templates. */
+    public ?bool $displayHeaderFooter = null;
+
+    /** Scale of webpage rendering (0.1 to 2.0). */
+    public ?float $scale = null;
+
+    /** Paper ranges to print, e.g. "1-3,5". */
+    public ?string $pageRanges = null;
+
+    /** Give CSS @page size priority over format. */
+    public ?bool $preferCSSPageSize = null;
+
+    /** Paper width with units (e.g. "8.5in"). Overrides format. */
+    public ?string $width = null;
+
+    /** Paper height with units (e.g. "11in"). Overrides format. */
+    public ?string $height = null;
+
+    public function toArray(): array
+    {
+        $data = [];
+        foreach ([
+            'format', 'landscape', 'margin', 'printBackground', 'filename',
+            'headerTemplate', 'footerTemplate', 'displayHeaderFooter',
+            'scale', 'pageRanges', 'preferCSSPageSize', 'width', 'height',
+        ] as $key) {
+            if ($this->$key !== null) {
+                $data[$key] = $this->$key;
+            }
+        }
+        return $data;
+    }
+}