fix: add cgo build tags to FrankenPHP files, add .gitignore

Co-Authored-By: Virgil <virgil@lethean.io>

.gitignore

@@ -0,0 +1 @@
+bin/

env.go

@@ -1,3 +1,5 @@
+//go:build cgo
+
 package php
 
 import (

handler.go

@@ -1,3 +1,5 @@
+//go:build cgo
+
 // Package php provides FrankenPHP embedding for Go applications.
 // Serves a Laravel application via the FrankenPHP runtime, with support
 // for Octane worker mode (in-memory, sub-ms responses) and standard mode