fix(apple/tvOS): television-idiomatic chrome — grid action tiles + full-screen covers

The iOS chrome half-worked on tvOS: toolbar items rendered tiny with clipped labels
and could not even be focused (which is why "+" never opened the add-host form), and
sheet presentations are not a tvOS idiom (the Settings form looked broken).

- The toolbar is gone on tvOS. Add Host and Settings live IN the hosts grid as
  full-size, focus-native tiles (.card style, same geometry as the host cards) — the
  natural way actions work on television.
- Every modal (Add Host, Settings, PIN pairing) presents as a fullScreenCover on tvOS;
  Settings gains a tvOS-only Done button (covers don't dismiss themselves).
- iOS/macOS keep their existing toolbar + sheets untouched.

Verified in the Apple TV simulator: title, host card and both action tiles render
full-size and focusable.

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

clients/apple/Sources/PunktfunkClient/SettingsView.swift

@@ -9,6 +9,7 @@ import PunktfunkKit
 import SwiftUI
 
 struct SettingsView: View {
+    @Environment(\.dismiss) private var dismiss
     @AppStorage("punktfunk.width") private var width = 1920
     @AppStorage("punktfunk.height") private var height = 1080
     @AppStorage("punktfunk.hz") private var hz = 60
@@ -99,6 +100,11 @@ struct SettingsView: View {
                     .font(.caption)
                     .foregroundStyle(.secondary)
             }
+            #if os(tvOS)
+            Section {
+                Button("Done") { dismiss() }
+            }
+            #endif
         }
         .formStyle(.grouped)
         #if os(macOS)