Add bare-minimum extension-reaper-macos REAPER extension skeleton

C/C++ extension built directly against the vendored Cockos reaper-sdk
headers (no Rust/reaper-rs wrapper layer). Loads, registers a test
action, and confirms via REAPER's console — confirmed working in
REAPER 2026-07-15.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

extension-reaper-macos/vendor/reaper-sdk/WDL/sc_bounce/stream-config.php

@@ -0,0 +1,21 @@
+<?php
+
+// some path that the server can write in (or create)
+$config_default_stream = "test"; // if no stream specified, use this one
+$config_session_timeout = 120; // seconds of inactivity = new session 
+$config_presend = 32000; // presend bytes on listener connect
+$config_keep_files = true; // keep old recordings
+
+// allowed servers, with their name, password, write path, optional listen password
+$config_streams = array(
+  "test" => array("password" => "somePassword", 
+                  "path" => "test_files",   // optional (stream name used if not specified)
+                  "session_timeout" => 120, // timeout in seconds ($config_session_timeout)
+                  "presend" => 32000,       // pre-send bytes ($config_presend)
+                  "keep_files" => true,
+                  "listen_password" => "",),
+
+);
+
+
+?>