Migrate journal entries to CoreData for iCloud sync (build 33)

- Add JournalEntry CoreData entity (syncable=YES): id, monthKey, note, moodRaw, rating, completionTime, createdAt
- Rewrite MonthlyCheckInStore: CoreData as primary storage, same public API
- One-time migration from UserDefaults triggered after store loads
- MonthlyCheckInCard: @FetchRequest on JournalEntry — reactive to iCloud sync
- MonthlyCheckInView: onReceive NSManagedObjectContextObjectsDidChange to refresh @State vars on sync
- Stats cards: observe NSManagedObjectContextObjectsDidChange instead of UserDefaults
- ChartsViewModel.completedMonthKeys: remove MonthlyCheckInStore dependency (data-driven)

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

PortfolioJournal/ViewModels/ChartsViewModel.swift

@@ -709,8 +709,7 @@ class ChartsViewModel: ObservableObject {
 
     private func completedMonthKeys(
         sources: [InvestmentSource],
-        snapshots: [Snapshot],
-        after cutoff: Date
+        snapshots: [Snapshot]
     ) -> Set<DateComponents> {
         let sourceIds = Set(sources.compactMap { $0.id })
         guard !sourceIds.isEmpty else { return [] }
@@ -723,9 +722,8 @@ class ChartsViewModel: ObservableObject {
         completed.reserveCapacity(groupedByMonth.count)
 
         for (key, monthSnapshots) in groupedByMonth {
-            guard let monthDate = Calendar.current.date(from: key) else { continue }
-            guard monthDate > cutoff else { continue }
-            guard MonthlyCheckInStore.completionDate(for: monthDate) != nil else { continue }
+            // A month is complete when all active sources have snapshot data for it.
+            // MonthlyCheckInStore (UserDefaults) is NOT synced via iCloud — don't use it as a filter.
             let monthSourceIds = Set(monthSnapshots.compactMap { $0.source?.id })
             if sourceIds.isSubset(of: monthSourceIds) {
                 completed.insert(key)
@@ -739,24 +737,8 @@ class ChartsViewModel: ObservableObject {
         sources: [InvestmentSource],
         snapshots: [Snapshot]
     ) -> [Snapshot] {
-        guard let lastCompleted = MonthlyCheckInStore.latestCompletionDate()?.startOfMonth else {
-            return snapshots
-        }
-
-        let completedMonthsAfter = completedMonthKeys(
-            sources: sources,
-            snapshots: snapshots,
-            after: lastCompleted
-        )
-
-        return snapshots.filter { snapshot in
-            let monthDate = chartMonthStart(for: snapshot.date)
-            if monthDate <= lastCompleted {
-                return true
-            }
-            let key = chartMonth(for: snapshot.date)
-            return completedMonthsAfter.contains(key)
-        }
+        let completedKeys = completedMonthKeys(sources: sources, snapshots: snapshots)
+        return snapshots.filter { completedKeys.contains(chartMonth(for: $0.date)) }
     }
 
     private func groupSnapshotsBySource(_ snapshots: [Snapshot]) -> [UUID: [Snapshot]] {