Phase 5h slice 5 — the Events tab's routing landed in slice 2; this
slice adds the dedicated-surface polish that distinguishes it from
the Events card on the Tasks tab.
Changes:
- Top header summary: 'N events · next 7 days' so m sees the window
shape at a glance without scanning rows.
- Day headings now carry three columns: the relative label
('Today' / 'Tomorrow' / weekday), the ISO date (mono font), and a
right-aligned event count. Bigger visual hierarchy than the cards-tab
flavour to justify the dedicated tab's existence.
- Empty-state copy invites linking a CalDAV calendar from a project's
detail page so a never-seen-events tab doesn't feel broken.
- StartLabel fallback to '—' when an event has no parseable start
time so the row doesn't collapse weirdly.
CSS adds .dash-events-summary, .event-day-heading flex layout,
.event-day-label / .event-day-date / .event-day-count spans, and a
constrained .dash-events-empty for the empty-state width.
Test: TestDashboardEventsViewRenders now also asserts the empty-state
copy ships, so a future refactor that drops the invite-to-link prose
gets caught.