Add bottom bar for navigation, tabs for inbox

[chrisirhc]

I'm currently just fiddling around and looking and what maybe needs to be refactored around to get a similar navigation as the current Zulip app.

At this stage, the PR is a set of minimal changes to make it look/feel closer to a slightly more polished navigation.

So far some findings:

• A more sophisticated router like go-router might be useful so that we can create deep links that follow the exact routing that the Zulip web client uses. Except with 1 main difference, specifying the server needs to be in the url.
  • Not sure what this would look like, perhaps: https://open.zulip.app/<serverIdentifier>/<path on zulip server>

Screen_recording_20240326_215102.webm

Note that the animations between the different navigation routes for the bottom navigation bar is slightly incorrect, since it uses a push animation that applies to the entire page including the navigation bar, rather than only animating/transitioning the main body area that's being changed.

Partially addresses #311

[Syrineladeb02]

Great work on this pull request, Chrisirhc!
I've thoroughly tested the changes you've made, and everything appears to be functioning smoothly.
I particularly appreciate the enhancements made to the navigation bar and the streamlined user experience it provides.

[gnprice]

Thanks @chrisirhc for exploring this and sending the PR!

We've more recently gotten around to thinking through what we want the navigation to look like, and I just wrote down a proper spec for it:

• Bottom tabs and main menu #1035

It overlaps with what this PR did, so I've added a link there saying this may be a useful starting point.

A more sophisticated router like go-router might be useful so that we can create deep links that follow the exact routing that the Zulip web client uses. Except with 1 main difference, specifying the server needs to be in the url.

• Not sure what this would look like, perhaps: https://open.zulip.app/<serverIdentifier>/<path on zulip server>

Yeah, deep links would be a useful feature but are tricky. Previous discussion here:

• Implement deep links #76