v0.5.6 — the hours page draws every hour of a day that opened before midnight

Reported live on /convo/: the hours breakdown was empty. Monday said
17h 13m and drew a single 23:00 row; Tuesday said 3h 32m and drew nothing
at all. Only Sunday — the one day nobody had worked across its opening
midnight — rendered. Every session was in the payload the whole time; the
client had no row to put them in.

• components/actors/Daysheet.tsx walks hour SLOTS, not hour NUMBERS.
  core/hours.py's edge rule credits an interval to the day its CLOSING
  stamp falls in, so a session opened at 23:5x and closed past midnight is
  filed under the NEXT day — and that day's local hours stop being monotone.
  The old for (h = first; h <= last; h += 1) then walked 23..23 (one row)
  or 23..10 (no rows). A slot is the local hour's own floor as a timestamp:
  monotone across any midnight, advanced through its successor's floor so a
  DST-stretched hour is one slot and a skipped one is none. The fold's
  identity is the slot too — such a pane can hold two rows labelled 23:00.
• Verified against the live /convo/ payload, not a fixture: Monday now
  draws 25 rows holding all 286 sessions, Tuesday 12 rows holding all 19, and
  each pane's total is exactly the sum of its rows. Sunday is unchanged.
• Pinned by ui/smoke/sections/daysheet-midnight-spill.tsx, with the old
  walk restored as a mutation and measured red.
• ui/smoke/sections/actors-window-filter.tsx repaired — it still pinned
  the calendar-month default that 0.5.5's successor replaced with the sliding
  30 days, and was red on master.