Diff parsing misinterprets file names for standard `diff` command

[jrk]

If I want to diff plain files, independent of git, the natural thing to do is something like:

diff -u file1.js file2.js | diff2html -i stdin

This generally works, but it does not parse the filenames correctly. diff by default renders the filename header like this:

--- file1.js	2025-04-06 13:33:10
+++ file2.js	2025-04-07 09:10:40

The parser swallows the timestamps as part of the filename, too, which (1) is distracting clutter and (2) breaks syntax highlighting since it can't interpret the file type from the suffix anymore.

getFilename in diff-parser.js should be able to strip off these suffixes. I think they're always rendered with a \t character between the filename and the time, so it should be pretty straightforward.

[jrk]

I was actually reading the generated installed JS and didn't notice the comment in the TS source that the regex at the end is already intended to strip off these dates.

So update on the above issue: I'm not immediately sure why, but this doesn't work at least with /usr/bin/diff on macOS, which outputs a header exactly as shown in the issue.