Improve support for todo widgets

[neiljp]

Initial work in #1549 by @rsashank provided

• parsing of todo data
• rendering into a styled message
• updating of the styled message upon changes in the server (events)

This issue is intended to split out todo-related follow-up work, part of which was originally tracked in #986.

Outstanding elements include

• Enable responding to tasks, ie. toggling the 'check mark' or 'done' status
• Allow editing the title in your own todo list
• Allow adding tasks to todo lists
• Limiting the editing of todo lists in the client (widget messages (content) may not be edited)

[AngathG]

@zulipbot claim

[zulipbot]

Welcome to Zulip, @AngathG! We just sent you an invite to collaborate on this repository at https://github.com/zulip/zulip-terminal/invitations. Please accept this invite in order to claim this issue and begin a fun, rewarding experience contributing to Zulip!

Here's some tips to get you off to a good start:

• Join me on the Zulip developers' server, to get help, chat about this issue, and meet the other developers.
• Unwatch this repository, so that you don't get 100 emails a day.

As you work on this issue, you'll also want to refer to the Zulip code contribution guide, as well as the rest of the developer documentation on that site.

See you on the other side (that is, the pull request side)!

[zulipbot]

@Shashwat-Harsh-dev This issue cannot be claimed, as someone else is already working on it. Please see our contributor guide for advice on finding an issue to work on. Thanks!

[neiljp]

@AngathG @Shashwat-Harsh-dev This has multiple parts, so if you wish to work on different pieces, that would be fine - or we can discuss on chat.zulip.org first, if some parts are not clear :)

[Subham-KRLX]

Hi @zulipbot and @neiljp! 👋

Thanks for starting this work on improving todo widget functionality in the terminal. It looks like a multi-part enhancement, and I’d be happy to help with specific sub-tasks. I’m particularly interested in:

• Implementing toggle behaviour for marking tasks as done/undone
• Allowing users to edit task titles in their own todo lists

Would it be okay if I picked one of these parts to work on and opened a PR for it? Happy to coordinate on chat.zulip.org if needed. Thanks!

[zulipbot]

@AngathG You have been unassigned from this issue because you have not made any updates for over 14 days. Please feel free to reclaim the issue if you decide to pick up again. Thanks!