[Epic]: Liveblogs in DCR for Apps

[JamieB-gu]

We want to make sure that DCR's liveblogs work correctly in the apps and that we maintain the same features that apps liveblogs previously had.

Apps Features

Something the apps support is signing up to alerts (notifications) for changes to a specific liveblog. We will want to replicate this behaviour for the apps version of DCR liveblogs. We may be able to draw on the UI changes that were made to accommodate this feature in AR in #3543, but this design differs from how the alert button currently looks in the apps, so it would be best to ask Design about which to use. It may be that we need to add a new Bridget service to handle this, or we may be able to reuse the existing Notifications service.

Required for launch in beta

### Features required for Beta
- [x] Support polling for new updates incl. toast message & re-rendering blocks
- [ ] https://github.com/guardian/dotcom-rendering/issues/10569
- [x] Support key events carousel (as in web)
- [ ] Update MAPI filter to allow dead blogs in beta
- [ ] https://github.com/guardian/dotcom-rendering/issues/10572
- [ ] https://github.com/guardian/dotcom-rendering/issues/9103
- [ ] https://github.com/guardian/dotcom-rendering/issues/10573

Required for launch in prod / live app

### Features required for PROD
- [ ] Offline reading
- [ ] Update MAPI filter to allow dead blogs in prod
- [ ] Update MAPI filter to allow live blogs in prod
- [ ] Sharebutton on liveblog blocks still awaiting design confirmation
- [ ] Reader revenue epic

### Full dark mode compatibility
- [ ] https://github.com/guardian/dotcom-rendering/issues/9531

### Non-essential features to support for post PROD release
- [ ] Infinite scrolling
- [ ] Key events filtering
- [ ] Smart filters/topics
- [ ] https://github.com/guardian/dotcom-rendering/issues/9572
- [ ] Message us
- [ ] https://github.com/guardian/dotcom-rendering/issues/9573

### Improvements or new features to build for post PROD release
- [ ] Improve bylines (https://github.com/guardian/dotcom-rendering/issues/10336)
- [ ] Expand the pinned post if it is the most recent post on the live blog (mentioned [here](https://github.com/guardian/dotcom-rendering/issues/8786#issuecomment-1766696178))
- [ ] https://github.com/guardian/dotcom-rendering/pull/9982

Existing Bugs

### Bugs
- [ ] When toggling light/dark mode, live blog content goes blank on legacy templates. [Chat link here](https://chat.google.com/room/AAAAehVq1H0/DwOmXjWdvtI/DwOmXjWdvtI?cls=10)

Local development improvements

### Local development improvements
- [ ] https://github.com/guardian/dotcom-rendering/issues/10167

Scratch doc

[rhiannareechaye]

Hello! Fyi a question came up about the 'pinned' post. The question was whether this should be truanted or expanded - Editorial confirmed that Truncated (which is what we've got on Web today) is the desired behaviour for app too. The only issue we have is when the 'pinned post' is the most recent post, it would be ideal for readers if it was expanded. This would be a new feature request and I don't think it's worth prioritising as part of this project, but potentially something to look at when/if we look at liveblogs again!