[CORE4] - Homepage and Navbar

1. Homepage has a dashboard showing events in Warchest that have been processed on Warchest since you were last logged in (think of these as alerts)
2. Alerts need to be dismissed (i.e with an X button) to be closed
3. Nav bar needs to be in a convenient spot, accessible across all pages and hideable

Start by locating the homepage and the shared navigation entry point, then trace how processed Warchest events and the last-login state are represented. Done means the homepage shows events since the previous login, alerts can be dismissed with an X, and the navigation is accessible and hideable across all pages.

Written by the indexing model from the issue text.