feature(metrics): Implement App Home metrics dashboard

[SpencerKaiser]

Pre-requisites:

• Yes, I looked through both open and closed issues looking for what I needed

Feature Description

The app should listen for the app_home_opened event and publish a view of blocks with metrics based on stats collected since the last restart:

• Total number of uses
• Number of unique users
• List of top channels and the number of posts per channel

The app should track these details in memory and include a header message saying when the tracking started (e.g., "Stats since last restart, which occurred at 7:31PM CST 7/20")