feat(live): Live Activity / Dynamic Island (WidgetKit extension iOS 16.2+/17+)

Nouvelle target "CoachLiveActivity" (Widget Extension, bundle
ch.hypnotruck.coach.LiveActivity, iOS 17.0) embarquée dans App via copy phase
"Embed App Extensions" (dstSubfolderSpec=13). API ActivityKit + WidgetKit
vérifiées sur SDK iOS 26.5 swiftinterface (Activity.request(content:),
ActivityConfiguration, DynamicIsland(expanded:compactLeading:trailing:minimal:)).

Architecture :
- CoachLiveActivityAttributes (modèle partagé App ↔ extension)
- CoachLiveActivityWidget (Lock Screen + Dynamic Island UI)
- CoachLiveActivityBundle (@main WidgetBundle)
- LiveActivityManager (App side, wrap Activity.request/update/end)
- LiveStore hook : start sur 1er sample, update à chaque ingest, end après
  60s "lost". Tout guardé @available(iOS 16.2, *) pour préserver deployment iOS 15.
- Info.plist App : NSSupportsLiveActivities = YES.

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

ios/App/CoachLiveActivity/Info.plist

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "https://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDisplayName</key>
+	<string>Coach Live</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>$(PRODUCT_BUNDLE_PACKAGE_TYPE)</string>
+	<key>CFBundleShortVersionString</key>
+	<string>$(MARKETING_VERSION)</string>
+	<key>CFBundleVersion</key>
+	<string>$(CURRENT_PROJECT_VERSION)</string>
+	<key>NSExtension</key>
+	<dict>
+		<key>NSExtensionPointIdentifier</key>
+		<string>com.apple.widgetkit-extension</string>
+	</dict>
+</dict>
+</plist>