feat(web): add multi-format report export (Markdown, HTML, PDF, Word,… (#756)

* feat(web): add multi-format report export (Markdown, HTML, PDF, Word, Image)

* fix: correct import order for docx (lint error)

* fix(web): address Copilot review comments for multi-format export

- Add i18n support for dropdown menu items (en/zh)

- Add DOMPurify for HTML sanitization (XSS protection)

- Fix async handling for canvas.toBlob with Promise wrapper

- Add toast notifications for export errors

- Fix Tooltip + DropdownMenuTrigger nesting (accessibility)

- Ensure container cleanup in finally block

* fix(web): enhance markdown parsing for PDF and Word export

- Add list support (bullet and numbered) for PDF export
- Add parseInlineMarkdown helper for Word export to handle bold, italic, code, links
- Add list support for Word export (bullet and numbered)
- Address Copilot review comments from PR #756

* fix(web): address PR review feedback for multi-format export

- Extract PDF formatting magic numbers into PDF_CONSTANTS

- Add Tooltip wrapper for download dropdown button

- Reduce triggerDownload cleanup timeout from 1000ms to 100ms

- Use marked.Lexer.lexInline for robust markdown parsing

- Add console.warn for image export cleanup errors

- Add numbering config for Word document ordered lists

- Fix CSS class typo: px-5pb-20 -> px-5 pb-20

- Remove unreachable dead code in parseInlineMarkdown

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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

web/messages/zh.json

@@ -130,7 +130,13 @@
       "generatePodcast": "生成播客",
       "edit": "编辑",
       "copy": "复制",
-      "downloadReport": "下载报告为 Markdown",
+      "downloadReport": "下载报告",
+      "downloadMarkdown": "Markdown (.md)",
+      "downloadHTML": "HTML (.html)",
+      "downloadPDF": "PDF (.pdf)",
+      "downloadWord": "Word (.docx)",
+      "downloadImage": "图片 (.png)",
+      "exportFailed": "导出失败，请重试",
       "searchingFor": "搜索",
       "reading": "阅读中",
       "runningPythonCode": "运行 Python 代码",