Add HIIT watch runner, rest-time setting, and HealthKit watch auto-launch

- Redesign the watch app into an active-workout runner: a root gate shows the
  in-progress workout's exercises or prompts to start one on iPhone, and each
  exercise runs as a horizontally-paged HIIT cycle (count-up work, count-down
  rest with final-three-second haptics + auto-advance, One More / Done on the
  last set). Replaces the old history list.
- Add a configurable rest-between-sets duration in iPhone Settings (default 45s),
  synced to the watch over WatchConnectivity.
- Launch the watch app into the session when a workout starts on the phone via
  HealthKit (startWatchApp); the watch runs an HKWorkoutSession for foreground
  runtime and ends it when the workout finishes. Adds the HealthKit entitlement +
  Health usage strings on both targets and WKBackgroundModes on the watch.

Claude-Session: https://claude.ai/code/session_018gg69MaUetDNzWzBXisfMV

Workouts Watch App/Resources/Info-watchOS.plist

@@ -22,6 +22,14 @@
 	<string>$(CURRENT_PROJECT_VERSION)</string>
 	<key>ITSAppUsesNonExemptEncryption</key>
 	<false/>
+	<key>NSHealthShareUsageDescription</key>
+	<string>Workouts uses Health to run a workout session on your watch so the app stays active while you train.</string>
+	<key>NSHealthUpdateUsageDescription</key>
+	<string>Workouts uses Health to run a workout session on your watch so the app stays active while you train.</string>
+	<key>WKBackgroundModes</key>
+	<array>
+		<string>workout-processing</string>
+	</array>
 	<key>WKApplication</key>
 	<true/>
 	<key>WKCompanionAppBundleIdentifier</key>

Workouts Watch App/Resources/Workouts-watchOS.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>