compose_box: Add start video call button in compose

[MritunjayTiwari14]

Fixes #1824

Design

Before	After	After(Clicking Button)
	R

Light Theme

XRecorder_20251015_04.mp4

Dark Theme

XRecorder_20251015_05.mp4

[gnprice]

Thanks. It looks like you still have a TODO item before this is ready to be reviewed, so marking it as draft for now.

[MritunjayTiwari14]

All the TODO are done @gnprice!

[gnprice]

Thanks. Before this can be reviewed, you'll need to revise it to have clear and coherent commits. See the instructions we discussed on a previous PR thread: #1830 (review)

[MritunjayTiwari14]

Thanks @gnprice for suggesting the refinement in commit history to make sure it becomes minimal and coherent. The same has been implemented.

[gnprice]

Thanks. Some of these commits aren't coherent. For example this commit f314a74:

    deps: Update pigeon to `26.0.2` from `26.0.1`
    
    This commit is the result of the following commands:
        flutter pub upgrade --major-version pigeon
        tools/check --all-files --fix pigeon
    
    Changelog:
    
    https://pub.dev/packages/pigeon/changelog#2602
---
 .../kotlin/com/zulip/flutter/AndroidIntents.g.kt    | Bin 6118 -> 6118 bytes
 .../com/zulip/flutter/AndroidNotifications.g.kt     | Bin 30643 -> 30643 bytes
 ios/Runner/Notifications.g.swift                    |   2 +-
 3 files changed, 1 insertion(+), 1 deletion(-)

can't be right, because it says it involved flutter pub upgrade but there's no change to pubspec.lock.

One useful step for spotting this kind of issue is to run our tests at every commit. If they fail, the commit needs fixing.

It's straightforward to do that by hand. But a command which can be a useful shortcut for it is this:
git rebase --exec 'tools/check --diff @~'

[MritunjayTiwari14]

Thank you @gnprice for taking time to review the commit history and for the useful shortcut. It was very handy and i was easily able to trace the coherent status of each commit and resolve them on the go.

Following i have done the updates in the commit history to maintain coherent commit with optimized minimalism.