cannot get filename from local pdf

When we read PDF from local storage, the hypothes.is cannot get the file name, but just shows "Untitled Document" in the comment management page. That's confusing whle reading multiple local PDFs.

We found a solution. If we put this pdf on a web server, then hypothes.is page change from "Untitled Document" to "my_filename_1.pdf", BUT it's only valid the first time. Even if we change the file to "my_filename_2.pdf" and visit from another web link. There's still "my_filename_1.pdf" as the title forever in comment management page ^^

No source file or test is identified in the issue. Reproduce the behavior by opening local PDFs and checking the comment management page, then trace how the document title is selected. Done means distinct local filenames appear correctly and opening another PDF does not retain the first title.

Written by the indexing model from the issue text.