* fix(collector): infer file extension from Content-Type for URLs without explicit extensions
When downloading files from URLs like https://arxiv.org/pdf/2307.10265,
the path has no recognizable file extension. The downloaded file gets
saved without an extension (or with a nonsensical one like .10265),
causing processSingleFile to reject it with 'File extension .10265
not supported for parsing'.
Fix: after downloading, check if the filename has a supported file
extension. If not, inspect the response Content-Type header and map
it to the correct extension using the existing ACCEPTED_MIMES table.
For example, a response with Content-Type: application/pdf will cause
the file to be saved with a .pdf extension, allowing it to be processed
correctly.
Fixes#4513
* small refactor
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Co-authored-by: Timothy Carambat <rambat1010@gmail.com>
2f7a818744