Special effects with emojis

On the desktop version of Element, whenever someone posts :tada: or :confetti_ball:, confetti falls down the screen. Snow falls for snow clouds. I like this feature, and would like to suggest it for Element iOS as well.

Start by reviewing how the desktop Element version triggers confetti for :tada: and :confetti_ball: and snow for snow-cloud messages, then trace the corresponding emoji and message-rendering entry points in Element iOS. Done means the iOS app provides equivalent effects with appropriate behavior and coverage, but the issue does not name specific files or tests.

Written by the indexing model from the issue text.