Fix ANR al terminar el import CSV (save + widget refresh por cada fila)

createSnapshot hacía save() por cada snapshot, y save() dispara refreshWidgetData
→ checkpointWAL (performAndWait en el viewContext main) + reloadAllTimelines. Con
213 snapshots eran 213 saves + 213 checkpoints en el main → Application Not
Responding. Añadido modo batch a createSnapshot (no guarda por fila; applyImport
ya guarda el contexto una vez al final) y flag suppressWidgetRefresh en
CoreDataStack para neutralizar el refresh por fila durante el import, con un único
refreshWidgetData al terminar.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L2p3gUZRNWW388rWFRjiU7

PortfolioJournal/Repositories/SnapshotRepository.swift

@@ -102,7 +102,8 @@ class SnapshotRepository: ObservableObject {
         date: Date = Date(),
         value: Decimal,
         contribution: Decimal? = nil,
-        notes: String? = nil
+        notes: String? = nil,
+        batch: Bool = false
     ) -> Snapshot {
         let snapshot = Snapshot(context: context)
         snapshot.source = source
@@ -113,7 +114,12 @@ class SnapshotRepository: ObservableObject {
         }
         snapshot.notes = notes
 
-        save()
+        // In batch mode (CSV import), skip the per-row save + widget refresh — the
+        // caller saves the whole context once at the end. Saving per row triggered a
+        // main-thread WAL checkpoint each time → ANR on large imports.
+        if !batch {
+            save()
+        }
         return snapshot
     }