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/CoachWatch.entitlements

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>com.apple.developer.healthkit</key>
+	<true/>
+	<key>com.apple.developer.healthkit.access</key>
+	<array/>
+</dict>
+</plist>