docs(ui5-ai-textarea): add docs and correct samples

do not restore previous value on generation cancelation

Author: ndeshev

packages/ai/test/pages/TextArea.html

@@ -366,7 +366,6 @@ <h1 class="demo-title">AI TextArea Component</h1>
 			stopTypingAnimation();
 			currentGenerationIndex += 1;
 
-			// Save the stopped generation if there is content
 			const stoppedValue = textarea.value;
 			if (stoppedValue.trim()) {
 				const menuItem = findMenuItemByAction(currentActionInProgress);
@@ -381,8 +380,6 @@ <h1 class="demo-title">AI TextArea Component</h1>
 					timestamp: new Date().toISOString()
 				});
 
-				// Restore the previous content
-				textarea.value = contentBeforeGeneration;
 				currentIndexHistory = versionHistory.length - 1;
 				buildMenuFromConfig();
 				updateComponentState();

packages/website/docs/_samples/ai/TextArea/Extended/main.js

@@ -270,7 +270,6 @@ function stopGeneration() {
 	stopTypingAnimation();
 	currentGenerationIndex += 1;
 
-	// Save the stopped generation if there is content
 	const stoppedValue = textarea.value;
 	if (stoppedValue.trim()) {
 		const action = currentActionInProgress || 'generate';
@@ -284,8 +283,6 @@ function stopGeneration() {
 			timestamp: new Date().toISOString()
 		});
 
-		// Restore the previous content
-		textarea.value = contentBeforeGeneration;
 		currentIndexHistory = versionHistory.length - 1;
 		buildMenuFromConfig();
 		updateComponentState();