refactor: the event row takes its clock instead of reading one

Every other surface here is handed `now` — the headline, the board, the dailies
strip, the detail sheet — for the reason the parsers are: a function that reads
the clock cannot be rendered against a fixed instant, so nothing about it can be
asserted. The list row was the one exception, calling the wall clock twice for
its window caption and its "starts in".

Two things follow from fixing it. Those numbers were counted from a different
instant than the `clock` sitting beside them in the same row, which is a
disagreement nobody would ever notice and nobody could ever prove. And the
countdown is now testable: rendering one row at two instants gives the two
answers the injected clock implies, which is what the new test pins.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

src/client/App.tsx

@@ -348,6 +348,7 @@ export function App() {
     <EventRow
       key={row.event.id}
       row={row}
+      now={now}
       completed={isDone(row.event.id)}
       status={prog.progress[row.event.id]?.status}
       effort={prog.progress[row.event.id]?.effort}