add a default predicted release date for entries with no predictable date

[xdeiimoss]

Describe your suggested feature

some way to choose a default frequency for all entries that doesn't have a predicted release date (even if it's completed (depending on the smart updates configuration)) the reason for the completed ones is that sometimes, the site will be marked as completed even though it isn't, which messes up smart updates.

Other details

No response

Acknowledgements

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• [X] If this is an issue with an official extension, I should be opening an issue in the extensions repository.
• [X] I have updated the app to version 1.11.1.
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