Further improve message send latency ($100)

[kevmo314]

muxable/rtchat#560 allows users to directly post to the actions collection, which allows faster writes instead of having to go through Firebase functions. The latter can be slow and unreliable, especially if signal is flaky, whereas the former is quite resilient. If signal is flaky, direct writes take a while but are still reliable.

Our frontend needs to be updated to directly write to the actions collection instead of calling the Firebase function as it does today.

The request is currently issued here: https://github.com/muxable/rtchat/blob/main/lib/models/adapters/actions.dart

The document structure should match:

The bounty for this request is $100 upon a successfully merged pull request. Please join our discord and message muxfd for access to #engineering, or post below for questions.