Merge main into more_checks, combining best of both branches

From main (22 commits):
- save-load.journal and save-load.get-by-url checks in PrepareCalendar
- CheckIsNotDefined with search.is-not-defined.category and .dtend sub-features
- Fine-tuned time-range checks (recent vs old dates) in CheckSearch
- post_filter=False everywhere for accurate server-side testing
- CheckCaseSensitiveSearch and CheckSubstringSearch
- Bedework compat fixes, stale year-2000 object cleanup
- Raw DELETE for delete-calendar, skip case-insensitive when no filtering
- test_ai_checks_with_mocks.py test suite

From more_checks (unique contributions):
- CheckDuplicateUID (cross-calendar duplicate UID detection, Zimbra handling)
- CheckSyncToken (RFC6578 sync token support)
- CheckFreeBusyQuery (RFC4791 freebusy query)
- CheckTimezone (non-UTC timezone event support, GitHub #372)

Conflict resolution improvements:
- save-load.get-by-url now uses permanent csc_simple_event1 instead of a
  temporary event - avoids create/delete cycle per the design principle
- CheckIsNotDefined now uses permanent csc_event_with_class and
  csc_event_with_duration events instead of temporary objects
- csc_event_with_class and csc_event_with_duration added to PrepareCalendar
- Updated test mocks to match permanent-event approach
- Fixed test_ai_filters test that documented the now-fixed date(1980) bug

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tobixen

src/caldav_server_tester/checker.py

@@ -70,6 +70,8 @@ def cleanup(self, force=True):
             self.calendar.delete()
             if self.tasklist != self.calendar:
                 self.tasklist.delete()
+            if self.journallist != self.calendar:
+                self.journallist.delete()
         else:
             for uid in (
                     "csc_simple_task1",
@@ -78,19 +80,27 @@ def cleanup(self, force=True):
                     "csc_simple_event3",
                     "csc_simple_event4",
                     "csc_event_with_categories",
+                    "csc_event_with_class",
+                    "csc_event_with_duration",
                     "csc_simple_task2",
                     "csc_simple_task3",
+                    "csc_simple_journal1",
                     "csc_monthly_recurring_event",
                     "csc_monthly_recurring_task",
-                    "csc_monthly_recurring_with_exception"):
+                    "csc_monthly_recurring_with_exception",
+                    "csc_recurring_count_task",
+                    "csc_url_check"):
                 try:
                     self.calendar.object_by_uid(uid).delete()
                 except:
                     try:
                         self.tasklist.object_by_uid(uid).delete()
                     except:
-                        ## TODO: investigate
-                        pass
+                        try:
+                            self.journallist.object_by_uid(uid).delete()
+                        except:
+                            ## TODO: investigate
+                            pass
 
     def report(self, verbose=False, return_what=str):
         ret = {