Fix gcal_delegate.py timestamp format

Remove redundant 'Z' suffix from isoformat() - timezone-aware
datetimes already include +00:00 offset, so appending 'Z' created
invalid RFC3339 timestamps that Google Calendar API rejected.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

mcp/delegation/gcal_delegate.py

@@ -79,8 +79,8 @@ def fetch_events(start: datetime, end: datetime, max_results: int = 50) -> list[
 
     events_result = service.events().list(
         calendarId='primary',
-        timeMin=start.isoformat() + 'Z',
-        timeMax=end.isoformat() + 'Z',
+        timeMin=start.isoformat(),
+        timeMax=end.isoformat(),
         maxResults=max_results,
         singleEvents=True,
         orderBy='startTime'