feat(watchos): UI live workout + entry point (Phase 2)

CoachWatchApp: WKApplicationDelegateAdaptor active WCSession au boot, injecte les
managers. ContentView: picker 4 activités (course/vélo/marche/renfo) -> vue live
(FC/calories/distance/durée + état liaison iPhone) -> bouton Terminer. Build OK.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ios/App/CoachWatch/CoachWatchApp.swift

@@ -1,10 +1,22 @@
 import SwiftUI
+import WatchKit
 
 @main
 struct CoachWatchApp: App {
+    @WKApplicationDelegateAdaptor private var appDelegate: WatchAppDelegate
+
     var body: some Scene {
         WindowGroup {
             ContentView()
+                .environmentObject(WorkoutManager.shared)
+                .environmentObject(ConnectivityManager.shared)
         }
     }
 }
+
+final class WatchAppDelegate: NSObject, WKApplicationDelegate {
+    func applicationDidFinishLaunching() {
+        // Active WCSession dès le boot pour ne rater aucun early message.
+        _ = ConnectivityManager.shared
+    }
+}