docs(skills): objectstack-query — timezone is the one passthrough key aggregate accepts

The passthrough paragraph said all six driver passthrough keys are illegal
on `count` and `aggregate`. `timezone` is one of the six and is a legal
option on `aggregate` in its own right — `ENGINE_AGGREGATE_OPTION_KEYS`
lists it and `aggregate()` reads it for date bucketing — which the row
above already showed. The paragraph now carves that one key out; `count`
still refuses it with the other five.

Claude-Session: https://claude.ai/code/session_01KTZmMfzVzjNvyaLyQ8mHvg
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

skills/objectstack-query/SKILL.md

@@ -39,7 +39,9 @@ The passthrough six ride along on `find`/`findOne` (and on `update`/`delete`)
 because there the option bag IS the base of the driver options, which is how an
 explicit `tenantId` reaches the driver. `count` and `aggregate` never forward the
 bag, so on those two the same keys are deliberately ILLEGAL — accepting them
-would be the silently-ignored option this check exists to close.
+would be the silently-ignored option this check exists to close. The one
+exception is `timezone`: `aggregate` reads it itself, for date bucketing, so it
+is legal there and the row above lists it; `count` refuses it with the rest.
 
 ### Which filter dialect?