Add a live status panel between the run screen's halves

Replaces the small target-HR pill on the iPhone run screen with a
glanceable big-digit strip between the timer flow and the figure —
heart rate (band-tinted with the cue arrow when the run carries a
target), HR zone, active calories, and the workout stopwatch. A
horizontal band in portrait, a vertical column in landscape (the
inverse of the half-and-half split, so it always sits between them).

The watch now rides the running calorie total and the HR zone (1-5,
computed watch-side where max HR is known) along with each live HR
sample; absent keys keep older builds wire-compatible both ways.
LiveRunState holds all three under the shared staleness expiry. The
screenshot rig seeds believable values so the run capture shows the
panel populated.

Shared/Connectivity/WCPayload.swift

@@ -149,13 +149,21 @@ enum WCPayload {
     // the readout refreshes on the next one.
     static let hrBpmKey = "hrBpm"
     static let hrAtKey = "hrAt"
+    static let hrKcalKey = "hrKcal"
+    static let hrZoneKey = "hrZone"
 
-    static func encodeLiveHeartRate(bpm: Double, at date: Date) -> [String: Any] {
-        [typeKey: liveHeartRateType, hrBpmKey: bpm, hrAtKey: date]
+    /// The session's running calories and HR zone ride along with each sample when
+    /// known — absent keys (an older watch, or no energy sample yet) decode as nil,
+    /// so the two builds stay wire-compatible in both directions.
+    static func encodeLiveHeartRate(bpm: Double, at date: Date, kcal: Double? = nil, zone: Int? = nil) -> [String: Any] {
+        var dict: [String: Any] = [typeKey: liveHeartRateType, hrBpmKey: bpm, hrAtKey: date]
+        if let kcal { dict[hrKcalKey] = kcal }
+        if let zone { dict[hrZoneKey] = zone }
+        return dict
     }
 
-    static func decodeLiveHeartRate(_ dict: [String: Any]) -> (bpm: Double, at: Date)? {
+    static func decodeLiveHeartRate(_ dict: [String: Any]) -> (bpm: Double, at: Date, kcal: Double?, zone: Int?)? {
         guard let bpm = dict[hrBpmKey] as? Double, let at = dict[hrAtKey] as? Date else { return nil }
-        return (bpm, at)
+        return (bpm, at, dict[hrKcalKey] as? Double, dict[hrZoneKey] as? Int)
     }
 }