Fix 7 data mutation layer risks identified in audit

- save()/saveAndRunDataListeners() now return @discardableResult Bool;
  listeners only fire on successful save
- MoodLogger.updateMood() now recalculates streak, updates Live Activity,
  and notifies watch (was missing these side effects)
- CSV import uses new addBatch()/importMoods() for O(1) side effects
  instead of O(n) per-row widget reloads and streak calcs
- Foreground task ordering: fillInMissingDates() now runs before
  removeDuplicates() so backfill-created duplicates are caught same cycle
- WidgetMoodSaver deletes ALL entries for date (was fetchLimit=1, leaving
  CloudKit sync duplicates behind)
- cleanupPhotoIfNeeded logs warning on failed photo deletion instead of
  silently orphaning files

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

Shared/Views/SettingsView/SettingsView.swift

@@ -775,7 +775,7 @@ struct SettingsContentView: View {
         ZStack {
             theme.currentTheme.secondaryBGColor
             Button {
-                DataController.shared.clearDB()
+                MoodLogger.shared.deleteAllData()
             } label: {
                 HStack(spacing: 12) {
                     Image(systemName: "trash")
@@ -1347,6 +1347,7 @@ struct SettingsView: View {
                     var rows = input.components(separatedBy: "\n")
                     guard !rows.isEmpty else { return }
                     rows.removeFirst()
+                    var importEntries: [(mood: Mood, date: Date, entryType: EntryType)] = []
                     for row in rows {
                         let stripped = row.replacingOccurrences(of: " +0000", with: "")
                         let columns = stripped.components(separatedBy: ",")
@@ -1359,10 +1360,9 @@ struct SettingsView: View {
                         }
                         let mood = Mood(rawValue: moodValue) ?? .missing
                         let entryType = EntryType(rawValue: Int(columns[2]) ?? 0) ?? .listView
-
-                        DataController.shared.add(mood: mood, forDate: forDate, entryType: entryType)
+                        importEntries.append((mood: mood, date: forDate, entryType: entryType))
                     }
-                    DataController.shared.saveAndRunDataListeners()
+                    MoodLogger.shared.importMoods(importEntries)
                     AnalyticsManager.shared.track(.importSucceeded)
                 } else {
                     AnalyticsManager.shared.track(.importFailed(error: nil))
@@ -1743,7 +1743,7 @@ struct SettingsView: View {
         ZStack {
             theme.currentTheme.secondaryBGColor
             Button(action: {
-                DataController.shared.clearDB()
+                MoodLogger.shared.deleteAllData()
             }, label: {
                 Text("Clear DB")
                     .foregroundColor(textColor)