fix(thumbnail): [PKG-TOOL-THUMB-04] supply public types and installed module entries

test/types/thumbnail-commonjs.cts

@@ -0,0 +1,14 @@
+// eslint-disable-next-line ts/no-require-imports -- Test the actual CommonJS constructor without interop helpers.
+import Thumbnail = require('artplayer-tool-thumbnail')
+// eslint-disable-next-line ts/no-require-imports -- The legacy subpath also directly exports its constructor.
+import Legacy = require('artplayer-tool-thumbnail/legacy')
+
+const option: Thumbnail.Option = { fileInput: document.createElement('input') }
+const tool: Thumbnail = new Thumbnail(option)
+const legacy: Thumbnail = new Legacy(option)
+const pending: Promise<void> = tool.start()
+tool.on('update', (url, progress) => url + progress.toFixed())
+void [legacy, pending]
+// @ts-expect-error No self-default constructor is exported.
+const WrongAlias = Thumbnail.default
+void WrongAlias