fix(worldclock): name offset-set zones by their real offset everywhere

The Etc/GMT-n naming fix only covered the local row. A home that
follows a device set by UTC offset still put "GMT-9" under a UTC+9
face. The rule now lives in the one place every row and the face take
their city from.

docs/ARCHITECTURE.md

@@ -2406,8 +2406,8 @@ that city already shows the local time. Home that follows the device can never
 differ from it, so with no stored home the rule is always null, and Settings ›
 Clock says so under the switch rather than hiding it. A device set by UTC
 offset rather than by city reports an id like `Etc/GMT-9`, whose last segment
-has its sign reversed, so that row is named by its real offset ("GMT+9")
-instead (`ZoneCatalog.hasPlaceName`).
+has its sign reversed, so that zone is named by its real offset ("GMT+9")
+instead, on the local row and on the face alike (`ZoneCatalog.hasPlaceName`).
 
 The row is not stored. It is `WorldClockUiState.Loaded.local`, built per tick
 by the source from the same `zones.current()` read the face uses, so a