app/static/index.html: opens an EventSource against /rounds/stream (no auth
needed, see the previous commit) alongside the existing polling loops. On an
"update" notification, immediately re-runs the same refreshes polling would
eventually do (refreshRound/refreshMe/checkLastRoundResult when logged in,
refreshChainStatusOnly when logged out). Also reacts to the browser's "open"
event, which fires on the initial connection and on every automatic
reconnect — this re-syncs right away instead of leaving the page on stale
state until the next event or poll tick, which matters most right after a
dropped connection comes back.
app/static/admin.html: same channel, refreshing the chain-status bar and
whichever admin section is currently open (Utenti/Round/Transazioni
pendenti/Audit log) instead of requiring a manual tab switch to see new data.
Polling intervals are untouched in both pages — this is purely additive, so
a blocked/dropped SSE connection just degrades to the pre-existing behavior.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>