feature request: Custom episode card thumbnail and synopsis

[folfoa]

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

Would be nice if it could customize the thumbnail and synopsis, especially if it's missing.

Proposed Solution

Add customization for thumbnail and synopsis
either by fetching from TVDB or locally like the extension for custom banner/cover