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>

pyproject.toml

@@ -3,7 +3,7 @@ name = "Radicale"
 # When the version is updated, a new section in the CHANGELOG.md file must be
 # added too.
 readme = "README.md"
-version = "3.7.6"
+version = "3.7.7.dev"
 authors = [{name = "Guillaume Ayoub", email = "guillaume.ayoub@kozea.fr"}, {name = "Unrud", email = "unrud@outlook.com"}, {name = "Peter Bieringer", email = "pb@bieringer.de"}]
 license = {text = "GNU GPL v3"}
 description = "CalDAV and CardDAV Server"