js: Add a place to start moving imports to C.

src/api.js.h

@@ -0,0 +1,18 @@
+#pragma once
+
+/**
+** \defgroup api_js JS API
+** Functions that are ultimately exposed to apps.
+** @{
+*/
+
+/** A JS context. */
+typedef struct JSContext JSContext;
+
+/**
+** Register JS API functions.
+** @param context The JS context.
+*/
+void tf_api_register(JSContext* context);
+
+/** @} */