修复无法获得pdf的问题

addon/locale/en-US/addon.ftl

@@ -126,6 +126,10 @@ lecture-playing-zh = Playing: translation
 lecture-status-ready-step2 = Ready: { $count } paragraphs + note synced
 lecture-no-pdf = No PDF attachment on this item
 lecture-attach-error = Cannot read PDF attachment
+lecture-attach-error-detail = Cannot read PDF attachment: { $detail }
+lecture-pdf-not-local = PDF is not available locally. Open the PDF in Zotero first, or ensure the attachment is synced or linked to a local file.
+lecture-pdf-file-missing = Local PDF file is missing or the path is invalid. Check Zotero storage settings or re-link the file.
+lecture-pdf-read-failed = Cannot read PDF file contents. Check that the file is valid and readable.
 lecture-mount-error = Failed to load voice lecture pane
 lecture-platform-hint-mac = macOS: set MinerU path under Preferences → ChatPapers → Voice lecture, or leave empty to use mineru on PATH.
 lecture-platform-hint-win = Windows: set the full path to mineru.exe under Preferences → ChatPapers → Voice lecture.

addon/locale/zh-CN/addon.ftl

@@ -126,6 +126,10 @@ lecture-playing-zh = 正在播放：中文讲解
 lecture-status-ready-step2 = 备课完成：{ $count } 段逐段精读可播放，笔记已同步
 lecture-no-pdf = 当前条目没有可用的 PDF 附件
 lecture-attach-error = 无法读取 PDF 附件
+lecture-attach-error-detail = 无法读取 PDF 附件：{ $detail }
+lecture-pdf-not-local = PDF 未下载到本地。请先在 Zotero 中双击打开该 PDF，或确认附件已同步/已链接到本机文件。
+lecture-pdf-file-missing = PDF 本地文件不存在或路径无效。请检查 Zotero 存储设置，或重新关联 PDF 文件。
+lecture-pdf-read-failed = 无法读取 PDF 文件内容。请确认文件未损坏，且 Zotero 有读取权限。
 lecture-mount-error = 语音伴读面板加载失败
 lecture-platform-hint-mac = macOS：MinerU 路径可在偏好设置 → ChatPapers → 语音伴读 中配置；留空则尝试 PATH 中的 mineru。
 lecture-platform-hint-win = Windows：请在偏好设置中填写 MinerU 可执行文件完整路径（如 mineru.exe）。