Filtering .ics calendar-subscriptions (e.g. hide all-day events)

Is your feature request related to a problem? Please describe.

I am subscribed to a company calendar, which is great, but includes a number of all-day events for projects that are ongoing. These events don't add any insight, so I would like to filter them out.

Describe the solution you'd like

In my case, a potential filter could target event categories or the all-day toggle. More generally, I would be good to be able to filter different properties of events.

This could be done in the settings for the individual subscription, either by selecting individual properties and in/excluding certain keywords, or through a regex.

Describe alternatives you've considered

I have in the past used icalfilter.com/ but it broke for me. Other sites offering this type of filtering only allow name and description as a filter. Also, I would really like to not go through one random website anymore.

No files, tests, or entry points are named. Start by tracing how .ics subscriptions are configured and imported, then define the supported event-property filtering scope and verify that selected filters exclude matching events without affecting other subscription data.