fix: 复查修复 5 处问题 — URL 双重转义/zen 泄漏/高亮环境不一致等

- parser: href/src/alt 改最小属性转义（escapeAttr 会把已实体化的 &
  再转义成 &，导致链接 URL 双重转义错误）；新增 URL/alt 防回归测试
- core: _pushHistory 增加 maxLength 兜底截断（exec/Tab/Smart Enter/括号
  自动闭合等程序化路径此前绕过 maxlength 限制）
- core: destroy 时清理 Zen 模式的 document mousemove 监听（此前泄漏）
- highlight: 自写环境无关转义（仅 & < >），修复 Node 环境下字符串高亮
  失效、浏览器与 SSR 输出不一致的问题
- floating-toolbar/context-menu: toggleFloatingToolbar/registerContextMenu
  恢复链式 return this（拆分时丢失）
- plugins: 补齐 3 个硬编码文案的 i18n（regex/shortcuts/imageTooLarge），
  6 种语言同步
- 测试 768 → 780

src/plugins.ts

@@ -323,7 +323,7 @@ const searchReplacePlugin: Plugin = {
       const selected = editor.textarea.value.substring(editor.textarea.selectionStart, editor.textarea.selectionEnd);
       const panel = document.createElement('div'); panel.className = 'me-search';
       panel.dataset.replace = showReplace ? '1' : '0';
-      panel.innerHTML = `<div class="me-search-row"><input type="text" class="me-search-find" placeholder="${t('searchPlaceholder')||'Find'}" value="${escapeAttr(selected)}"/><button class="me-search-btn me-search-prev" title="${t('findPrev')||'Previous'}"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"><polyline points="18 15 12 9 6 15"/></svg></button><button class="me-search-btn me-search-next" title="${t('findNext')||'Next'}"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"><polyline points="6 9 12 15 18 9"/></svg></button><span class="me-search-count"></span><button class="me-search-btn me-search-case me-active" title="${t('matchCase')||'Match Case'}">Aa</button><button class="me-search-btn me-search-word" title="${t('wholeWord')||'Whole Word'}">ab</button><button class="me-search-btn me-search-regex" title="Regex">.*</button><button class="me-search-btn me-search-close" title="${t('close')||'Close'}"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"><line x1="18" y1="6" x2="6" y2="18"/><line x1="6" y1="6" x2="18" y2="18"/></svg></button></div><div class="me-search-row me-search-replace-row"><input type="text" class="me-search-replace" placeholder="${t('replacePlaceholder')||'Replace'}"/><button class="me-search-btn me-search-replace-one">${t('replace')||'Replace'}</button><button class="me-search-btn me-search-replace-all">${t('replaceAll')||'All'}</button></div>`;
+      panel.innerHTML = `<div class="me-search-row"><input type="text" class="me-search-find" placeholder="${t('searchPlaceholder')||'Find'}" value="${escapeAttr(selected)}"/><button class="me-search-btn me-search-prev" title="${t('findPrev')||'Previous'}"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"><polyline points="18 15 12 9 6 15"/></svg></button><button class="me-search-btn me-search-next" title="${t('findNext')||'Next'}"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"><polyline points="6 9 12 15 18 9"/></svg></button><span class="me-search-count"></span><button class="me-search-btn me-search-case me-active" title="${t('matchCase')||'Match Case'}">Aa</button><button class="me-search-btn me-search-word" title="${t('wholeWord')||'Whole Word'}">ab</button><button class="me-search-btn me-search-regex" title="${t('regex')||'Regex'}">.*</button><button class="me-search-btn me-search-close" title="${t('close')||'Close'}"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"><line x1="18" y1="6" x2="6" y2="18"/><line x1="6" y1="6" x2="18" y2="18"/></svg></button></div><div class="me-search-row me-search-replace-row"><input type="text" class="me-search-replace" placeholder="${t('replacePlaceholder')||'Replace'}"/><button class="me-search-btn me-search-replace-one">${t('replace')||'Replace'}</button><button class="me-search-btn me-search-replace-all">${t('replaceAll')||'All'}</button></div>`;
       editor.el.appendChild(panel); state._panel = panel;
       _updateReplaceVisible();
       state._regexMode = false; state._matchCase = true; state._wholeWord = false;
@@ -483,7 +483,7 @@ const imagePastePlugin: Plugin = {
           const sizeKB = file.size / 1024;
           if (maxSizeKB > 0 && sizeKB > maxSizeKB) {
             e.preventDefault();
-            if (typeof editor.toast === 'function') editor.toast(`Image too large (${sizeKB.toFixed(0)}KB > ${maxSizeKB}KB)`, { type: 'warning' });
+            if (typeof editor.toast === 'function') editor.toast(t('imageTooLarge', { size: sizeKB.toFixed(0), max: maxSizeKB }) || `Image too large (${sizeKB.toFixed(0)}KB > ${maxSizeKB}KB)`, { type: 'warning' });
             break;
           }
           e.preventDefault();
@@ -527,11 +527,11 @@ const shortcutHelpPlugin: Plugin = {
         ['Ctrl+Y', t('redo') || 'Redo'], ['Ctrl+S', t('save') || 'Save'],
         ['Ctrl+F', t('search') || 'Search'], ['Ctrl+H', t('replace') || 'Replace'],
         ['Tab', t('indent') || 'Indent'], ['Shift+Tab', t('outdent') || 'Outdent'],
-        ['?', t('close') || 'Shortcuts'],
+        ['?', t('shortcuts') || 'Shortcuts'],
       ];
       let rows = ''; builtin.forEach(([c, d]) => { rows += `<tr><td>${c}</td><td>${d}</td></tr>`; });
       const overlay = document.createElement('div'); overlay.className = 'me-shortcut-overlay';
-      overlay.innerHTML = `<div class="me-shortcut-panel"><h3>⌨️ ${t('close') || 'Shortcuts'}</h3><button class="me-shortcut-close">×</button><table>${rows}</table></div>`;
+      overlay.innerHTML = `<div class="me-shortcut-panel"><h3>⌨️ ${t('shortcuts') || 'Shortcuts'}</h3><button class="me-shortcut-close">×</button><table>${rows}</table></div>`;
       overlay.addEventListener('click', (e) => { if (e.target === overlay || (e.target as HTMLElement).classList.contains('me-shortcut-close')) _close(); });
       document.body.appendChild(overlay); _panel = overlay;
     };