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/composer.json

@@ -0,0 +1,24 @@
+{
+  "name": "docfast/docfast-php",
+  "description": "Official PHP SDK for the DocFast HTML/Markdown to PDF API",
+  "type": "library",
+  "license": "MIT",
+  "homepage": "https://docfast.dev",
+  "keywords": ["pdf", "html-to-pdf", "markdown-to-pdf", "api", "docfast"],
+  "require": {
+    "php": "^8.1",
+    "ext-json": "*",
+    "ext-curl": "*"
+  },
+  "autoload": {
+    "psr-4": {
+      "DocFast\\": "src/"
+    }
+  },
+  "authors": [
+    {
+      "name": "DocFast",
+      "homepage": "https://docfast.dev"
+    }
+  ]
+}