refactor(iframe): [PKG-IFRAME-04] preserve types across module consumers

packages/artplayer-tool-iframe/README.md

@@ -6,6 +6,35 @@ Iframe tool for ArtPlayer
 
 [https://artplayer.org](https://artplayer.org/?libs=./uncompiled/artplayer-tool-iframe/index.js&example=iframe)
 
+## TypeScript
+
+Default imports keep the historical class signatures, including `resove`,
+required message `data`, and the original `commit` result inference. Named types
+include `Option`, `Message`, `ProtocolMessage` and optional runtime views:
+
+```ts
+import type { ResolverInstance, RuntimeConstructor } from 'artplayer-tool-iframe'
+import Iframe from 'artplayer-tool-iframe'
+
+const Runtime = Iframe as RuntimeConstructor
+const tool = new Runtime({ iframe: document.querySelector('iframe')!, url: '/iframe.html' })
+const resolver = tool as ResolverInstance
+const value = await resolver.commit<number>((resolve) => {
+  resolve(42)
+})
+```
+
+`commit` serializes the function body. Keep its braces, use the literal `resolve`
+name for asynchronous replies, and do not depend on closures or an async function
+body. Handle rejection when the child document changes or the tool is destroyed.
+The runtime views are types only; they do not validate messages or sandbox code.
+
+The browser global is `ArtplayerToolIframe`. Modern TypeScript CommonJS consumers
+can use `import Iframe = require('artplayer-tool-iframe')`; older Node resolution
+uses the default import with `esModuleInterop`. The class has no `.default`
+property. The historical `artplayer-plugin-iframe` package and its separate helper
+have different export/protocol details; they are not aliases for this tool.
+
 ## Maintenance
 
 See [ARCHITECTURE.md](ARCHITECTURE.md) for the TypeScript module map, request