feature request: Local source support for Manga

[UnTamed-Fury]

Checklist

• I checked that this feature has not been requested before
• I checked that this feature is not in the "Not planned" list
• This feature will benefit the majority of users

Problem Description / Use Case

The manga viewer in the Seanime client is really good. If it could support locally hosted PDF files, like downloaded manga or other PDFs, it would be much more useful.

Note: I used AI to write this because my writing skills aren’t great.

Proposed Solution

Add a feature to import and view local PDF files within the existing manga viewer interface.

Provide options to organize and access these files from a dedicated "Local Files" section.