Wire the derived UnreadPresence into dot indicators (no counts) across the
navigation panel: workspace, project, and machine rows (machine-switcher and
machine-list) now show a static accent dot whenever a session beneath them is
unread, including offline machines with stale-but-present state. Presence
flows PiWebApp -> AppNavigationPanel -> leaf id sets, mirroring the
unreadSessionIds chain, and is covered by happy-dom component tests per list
plus panel- and app-level wiring tests. Adds changesets for the mark-as-read
actions and the bubble-up indicators.
