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>

CHANGELOG.md

@@ -1,5 +1,8 @@
 # Changelog
 
+## 3.7.7.dev
+* Fix: time-range filter treated a VEVENT with a whole-day DURATION (e.g. P1D, P2D) as zero-length (timedelta.seconds instead of total_seconds), so such events were missing from calendar-query REPORT results
+
 ## 3.7.6
 * Extension: item verification on commandline
 * Improvement: catch lack of support of PERIOD in vobject <= 0.9.9