Fix 25 audit issues: memory leaks, concurrency, performance, accessibility

Address findings from comprehensive audit across 5 workstreams:

- Memory: Token-based DataController listeners (prevent closure leaks),
  static DateFormatters, ImageCache observer cleanup, MotionManager
  reference counting, FoundationModels dedup guard
- Concurrency: Replace Task.detached with Task in FeelsApp (preserve
  MainActor isolation), wrap WatchConnectivity handler in MainActor
- Performance: Cache sortedGroupedData in DayViewViewModel, cache demo
  data in MonthView/YearView, remove broken ReduceMotionModifier
- Accessibility: VoiceOver support for LockScreen, DemoHeatmapCell
  labels, MonthCard button labels, InsightsView header traits,
  Smart Invert protection on neon headers

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Shared/Services/WatchConnectivityManager.swift

@@ -153,35 +153,32 @@ extension WatchConnectivityManager: WCSessionDelegate {
     }
 
     private func handleReceivedMessage(_ message: [String: Any]) {
-        guard let action = message["action"] as? String else {
-            Self.logger.error("No action in message")
-            return
-        }
-
-        switch action {
-        case "logMood":
-            guard let moodRaw = message["mood"] as? Int,
-                  let mood = Mood(rawValue: moodRaw),
-                  let timestamp = message["date"] as? TimeInterval else {
-                Self.logger.error("Invalid mood message format")
+        Task { @MainActor in
+            guard let action = message["action"] as? String else {
+                Self.logger.error("No action in message")
                 return
             }
 
-            let date = Date(timeIntervalSince1970: timestamp)
-            Self.logger.info("Processing mood \(moodRaw) from watch for \(date)")
+            switch action {
+            case "logMood":
+                guard let moodRaw = message["mood"] as? Int,
+                      let mood = Mood(rawValue: moodRaw),
+                      let timestamp = message["date"] as? TimeInterval else {
+                    Self.logger.error("Invalid mood message format")
+                    return
+                }
 
-            Task { @MainActor in
+                let date = Date(timeIntervalSince1970: timestamp)
+                Self.logger.info("Processing mood \(moodRaw) from watch for \(date)")
                 MoodLogger.shared.logMood(mood, for: date, entryType: .watch)
-            }
 
-        case "reloadWidgets":
-            Self.logger.info("Received reloadWidgets from watch")
-            Task { @MainActor in
+            case "reloadWidgets":
+                Self.logger.info("Received reloadWidgets from watch")
                 WidgetCenter.shared.reloadAllTimelines()
-            }
 
-        default:
-            Self.logger.warning("Unknown action: \(action)")
+            default:
+                Self.logger.warning("Unknown action: \(action)")
+            }
         }
     }
     #endif