Fix: expand REPORT leaves recurrence properties on expanded instances

_strip_single_event() removed the recurrence-defining properties (RRULE,
EXDATE, EXRULE, RDATE) with a single try/except around sequential
delattr() calls. When one of them was absent (e.g. an event with no
EXDATE), the AttributeError aborted the whole block and the following
properties -- notably RDATE -- were left on the expanded
single-occurrence VEVENTs returned by a calendar-data expand REPORT.

Remove each property independently so a missing one no longer prevents
removal of the others. Add a regression test and fixture.

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

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## 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
+* Fix: calendar-data expand (REPORT) left recurrence properties (e.g. RDATE) on the expanded single-occurrence VEVENTs; a single try/except around the sequential delattr() calls stopped at the first absent property (e.g. missing EXDATE), so later ones were never removed
 
 ## 3.7.6
 * Extension: item verification on commandline