Fix: time-range filter matches VEVENT with whole-day DURATION

A calendar-query REPORT with a time-range filter failed to return a
VEVENT that has a whole-day DURATION (e.g. DURATION:P1D or P2D) whenever
the queried range fell inside the event but after DTSTART.

The VEVENT time-range logic in radicale/item/filter.py gated the
"non-zero duration" branch (rfc4791-9.9 line 2) on timedelta.seconds
instead of timedelta.total_seconds(). For a duration that is an exact
multiple of 24h, timedelta.seconds is 0 (the days component holds the
value), so the event was treated as zero-length (line 3) and only
matched a one-second window at its start. An identical event expressed
with DTEND matched correctly, confirming the defect is isolated to the
DURATION path.

Use total_seconds() so multi-day durations are handled correctly. Adds a
regression test (event11, DURATION:P2D) covering both an inside-range
match and an outside-range non-match.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

radicale/tests/static/event11.ics

@@ -0,0 +1,11 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Radicale//NONSGML Radicale Server//EN
+BEGIN:VEVENT
+DTSTAMP:20130901T000000Z
+UID:event11
+SUMMARY:event11
+DTSTART:20130901T000000Z
+DURATION:P2D
+END:VEVENT
+END:VCALENDAR