feat(watchos): target CoachWatch (Phase 1) — app watchOS embarquée

- nouvelle target watchOS app CoachWatch (ch.hypnotruck.coach.watchkitapp), SwiftUI, SDK watchos
- entitlement HealthKit + Info.plist FR (NSHealthShare/UpdateUsageDescription) + WKBackgroundModes workout-processing
- "Embed Watch Content" + dépendance App -> CoachWatch (CoachWatch.app dans App.app/Watch)
- schemes partagés App + CoachWatch
- CoachWatchApp.swift + ContentView.swift minimaux

Build validé: target watchsimulator + embed dans App.app (iphonesimulator).

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

ios/App/CoachWatch/ContentView.swift

@@ -0,0 +1,20 @@
+import SwiftUI
+
+struct ContentView: View {
+    var body: some View {
+        VStack(spacing: 8) {
+            Image(systemName: "heart.fill")
+                .foregroundStyle(.red)
+            Text("Coach")
+                .font(.headline)
+            Text("Prêt")
+                .font(.caption)
+                .foregroundStyle(.secondary)
+        }
+        .padding()
+    }
+}
+
+#Preview {
+    ContentView()
+}