refactor(submit): drop the hover block-delete overlay

Hovering a quote, hidden block, code block or table showed a ✕ button in the
block's top-right corner. It read as a stray close button and is not wanted.

Removed
- installBlockActions() and the two-step select/delete flow it drove
- the block-actions markup, positioning, selected-state CSS in the iframe
  content style
- BLOCK_SELECTOR, which only the overlay used

Deleting blocks still works: removeAdjacentBlock() keeps Backspace / Delete
next to a structural block (table, pre, hr, quote, hidden block) working, and
that is covered by both code and tests.

tests/widget-system/creator-studio-contract.test.cjs

@@ -312,38 +312,25 @@ test('top bar is masthead + centered toolbar, with no brand text in the toolbar
 	assert.doesNotMatch(rest, /'home'\s*=>\s*esc_url_raw\(\$home\)/);
 });
 
-test('block delete overlay lives outside the editable body and stays hidden', () => {
+// 块右上角的悬停删除浮层已移除：删除统一走键盘（退格 / Delete）与工具栏。
+// 浮层留在这里会被误当成「不需要的关闭按钮」，也曾在 body 里破坏 mceInsertContent。
+test('hover block-delete overlay is gone', () => {
 	const runtime = read('assets/creator-studio/src/editor-runtime.ts');
 	const contentStyle = read('assets/creator-studio/src/editor-content-style.ts');
-	const pageStyles = read('assets/creator-studio/src/styles/_block-tools.scss');
+	const app = read('assets/creator-studio/src/index.tsx');
 
-	// 浮层挂在 iframe 的 documentElement 上，不能进 body：data-mce-bogus 只跳过
-	// 序列化，body 里多一个非常规子节点会让 mceInsertContent 把整篇正文清空
-	// （表现为「第一次点隐藏块没有插进正文」）。
-	assert.match(runtime, /doc\.documentElement\.appendChild\(bar\)/);
-	assert.doesNotMatch(runtime, /doc\.body\.appendChild\(bar\)/);
-	assert.match(runtime, /bar\.id = 'jio-block-actions'/);
-	// iframe 是独立文档：页面级样式表管不到它，隐藏规则必须写在 content_style。
-	assert.match(contentStyle, /#jio-block-actions\s*\{[^}]*position:\s*absolute/);
-	assert.match(contentStyle, /#jio-block-actions\s*\{[^}]*opacity:\s*0/);
-	assert.match(contentStyle, /#jio-block-actions\.is-visible\s*\{[^}]*opacity:\s*1/);
-	assert.match(contentStyle, /body\s*\{[^}]*position:\s*relative/);
-	// 页面级 SCSS 不再重复定义 iframe 内部的选择器（否则只是死样式）。
-	assert.doesNotMatch(pageStyles, /\.jio-creator__block-actions\s*\{/);
-	// data-mce-bogus 让 TinyMCE 序列化、字数和选区都跳过这个浮层。
-	assert.match(runtime, /setAttribute\('data-mce-bogus', 'all'\)/);
+	assert.doesNotMatch(runtime, /jio-block-actions/);
+	assert.doesNotMatch(runtime, /jio-creator__block-actions/);
+	assert.doesNotMatch(runtime, /installBlockActions/);
+	assert.doesNotMatch(runtime, /BLOCK_SELECTOR/);
+	assert.doesNotMatch(contentStyle, /jio-block-actions/);
+	assert.doesNotMatch(contentStyle, /jio-creator__block-selected/);
+	assert.doesNotMatch(app, /installBlockActions/);
 
-	// 两步删除：第一次点击只选中，第二次才真删；不再有关闭 / 叉号语义。
-	const firstClick = runtime.indexOf('if (selected !== block) {');
-	const secondClick = runtime.indexOf('// 第二次点击：真正删除。');
-	assert.ok(firstClick !== -1 && secondClick !== -1, 'two-step delete branches both exist');
-	assert.ok(firstClick < secondClick, 'first click only selects');
-	assert.ok(
-		runtime.indexOf('block.classList.add(SELECTED_CLASS)', firstClick) < secondClick,
-		'selection class is applied on the first click'
-	);
-	assert.match(contentStyle, /\.jio-creator__block-selected\s*\{/);
-	assert.match(runtime, /再次点击删除此块/);
+	// 键盘删除仍然保留：空段落旁的结构块要能被退格删掉。
+	assert.match(runtime, /export function removeAdjacentBlock/);
+	assert.match(runtime, /STRUCTURAL_SELECTOR/);
+	assert.match(app, /removeAdjacentBlock\(editor, event\)/);
 });
 
 // 工具栏下拉：菜单必须 portal 到 body，否则会被横向滚动的工具条裁剪。

tests/widget-system/submit-placeholder-behavior.test.cjs

@@ -140,13 +140,13 @@ test('placeholder never becomes a DOM node in the editable body', () => {
 });
 
 test('editor chrome injected into the body does not count as content', () => {
-  // 真实页面上 editor-runtime 会把块删除浮层插进 body，它带 data-mce-bogus
-  // 但含文字（「✕ 选中此块」）。若按 body.textContent 判断，空正文永远非空，
-  // 占位符就永远不显示 —— 这正是「首次加载不显示」的真实原因。
+  // TinyMCE 会往 body 里插带 data-mce-bogus 的工具节点，其中可能含文字。
+  // 若按 body.textContent 判断，空正文永远非空，占位符就永远不显示 ——
+  // 这正是「首次加载不显示」的真实原因。
   const { doc, editor } = createEditor(
     '<p><br data-mce-bogus="1"></p>' +
-      '<div id="jio-block-actions" data-mce-bogus="all">' +
-      '<button type="button"><span>✕</span><span>选中此块</span></button></div>',
+      '<div data-mce-bogus="all">' +
+      '<button type="button"><span>✕</span><span>工具节点</span></button></div>',
     { placeholder: '请输入正文' }
   );
   const plugin = loadPlugin()[PLUGIN];