Make Apple Health workout recording watch-only

The phone no longer writes estimated Health workouts: the watch, which
runs the live session, is the sole recorder. Replaces WorkoutHealthWriter
with a WorkoutHealthDeleter that only removes a legacy phone-estimate
workout when its record is deleted here, drops the MET calorie table and
the phone's write/read Health scopes, and keeps phoneEstimate decodable
for existing documents.

Claude-Session: https://claude.ai/code/session_01HJDQQDA9QdP8zByg43H5v3

Workouts/Sync/SyncEngine.swift

@@ -51,14 +51,6 @@ final class SyncEngine {
     /// this to push fresh state to the watch.
     var onCacheChanged: (() -> Void)?
 
-    /// Called when a completed workout is persisted. The HealthKit writer uses this to
-    /// schedule an estimated Health workout if nothing recorded it.
-    var onWorkoutCompleted: ((WorkoutDocument) -> Void)?
-
-    /// Called when a workout carrying watch-recorded metrics is persisted, so the
-    /// writer can cancel any pending phone estimate for it.
-    var onWatchMetricsArrived: ((String) -> Void)?
-
     private let log = Logger(subsystem: "dev.rzen.indie.Workouts", category: "sync")
     private let modelContainer: ModelContainer
     private var store: DocumentFileStore?
@@ -351,10 +343,6 @@ final class SyncEngine {
         } catch {
             report("Failed to save workout", error)
         }
-        // Drive the HealthKit writer: a watch-recorded doc cancels any pending estimate;
-        // a completed doc (re)considers an estimate (the writer dedupes on metrics).
-        if doc.metrics?.source == .watch { onWatchMetricsArrived?(doc.id) }
-        if doc.status == WorkoutStatus.completed.rawValue { onWorkoutCompleted?(doc) }
     }
 
     func delete(split: Split) async {