feat: Refactor global event handling in ArtPlayer

- Introduced a new globalInit function to manage document and window events.
- Replaced direct event proxies with a unified bindGlobalEvents method.
- Updated event handling in various modules to utilize the new global event system.
- Removed the deprecated documentInit module.
- Bumped version to 5.2.6 in package.json.

docs/uncompiled/artplayer-plugin-document-pip/index.js

@@ -256,6 +256,7 @@ function artplayerPluginDocumentPip(userOptions = {}) {
                     pipWin.removeEventListener('unload', onClose);
                 };
                 addClass($player, 'artplayer-document-pip');
+                art.events.bindGlobalEvents?.();
                 art.emit('document-pip', true);
             } catch (err) {
                 art.notice.show = 'Document Picture-in-Picture open failed';
@@ -279,6 +280,7 @@ function artplayerPluginDocumentPip(userOptions = {}) {
                 state.win.close();
                 state.win = null;
                 removeClass($player, 'artplayer-document-pip');
+                art.events.bindGlobalEvents?.();
                 art.emit('document-pip', false);
             } catch (err) {
                 art.notice.show = 'Document Picture-in-Picture close failed';