fix(zbugs-swift): show the issue count in full on iPhone and iPad (#199)

The list's toolbar gave the count a few characters' width, so 16,155
read as "16…". At its fixed size it shows in full; macOS is unchanged.

Amp-Thread-ID: https://ampcode.com/threads/T-09cae685-ab24-4553-a84f-3ace30fd7ad4

Co-authored-by: Amp <amp@ampcode.com>

Author: tmm

apps/zbugs-swift/Sources/ZBugsUI/RootView.swift

@@ -224,6 +224,9 @@
         IssueCount(filter: filter, list: issues)
           .foregroundStyle(.secondary)
           .monospacedDigit()
+          // At its full width: an iPhone's or an iPad's navigation bar
+          // otherwise gives it a few characters' width and truncates it.
+          .fixedSize()
       }
       ToolbarItem {
         ConnectionBadge(connection: model.zero.connection)