fix(ui): window title Ch∆In Studio (was F∆I); de-dup federation add-satellite

- linux/macOS window chrome read 'F∆I Studio' (rename leftover) → 'Ch∆In Studio'.
- The federation page showed 'Add satellite' twice when empty (FAB + empty-state
  button); drop the empty-state button, the FAB carries the action.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/pages/federation.dart

@@ -131,15 +131,13 @@ class _FederationPageState extends State<FederationPage> {
           }
           final sats = snapshot.data ?? [];
           if (sats.isEmpty) {
+            // The "add satellite" action lives in the FAB (always
+            // visible); don't repeat it here — that showed the button
+            // twice on the empty page.
             return ChainEmptyState(
               icon: Icons.hub_outlined,
               title: l.federationEmptyTitle,
               hint: l.federationEmptyHint,
-              action: FilledButton.icon(
-                onPressed: _addSatellite,
-                icon: const Icon(Icons.add_link, size: 16),
-                label: Text(l.federationAddSatellite),
-              ),
             );
           }
           return ListView.separated(