fix(apple/iOS): touch-first control sizing — toolbar circles + large sheet buttons

The iOS chrome inherited macOS dialog sizing and read as undersized on a phone:

- Toolbar: the two trailing actions shared one compact glass pill; on iOS 26+ each now
  gets its own full-size circle (explicit .topBarTrailing placements split by a fixed
  ToolbarSpacer — the system-app look, e.g. Files), with the grouped-pill fallback on
  iOS 17–18. The buttons are extracted so macOS keeps SettingsLink + .help untouched.
- Sheets and CTAs (AddHostSheet, PairSheet, trust card, empty-state Add Host) get
  .controlSize(.large) on iOS — proper touch targets instead of macOS dialog buttons.

Verified in the iPhone 17 simulator: two ~44 pt glass circles matching the Files app's
toolbar sizing; macOS suite and app build unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/apple/Sources/PunktfunkClient/AddHostSheet.swift

@@ -34,6 +34,9 @@ struct AddHostSheet: View {
                 .keyboardShortcut(.defaultAction)
                 .disabled(address.trimmingCharacters(in: .whitespaces).isEmpty)
             }
+            #if os(iOS)
+            .controlSize(.large)
+            #endif
             .padding(16)
         }
         #if os(macOS)