Implement storage architecture from ai_blueprint.md

Primary sync: replace PersistenceActor JSON file with SwiftData + CloudKit
- Add SavedCardModel (@Model class) and PersistenceController (ModelContainer
  with .automatic CloudKit, fallback to local). BackgroundPersistenceActor
  (@ModelActor) handles all DB I/O off the main thread.
- One-time migration imports user_collection.json into SwiftData and renames
  the original file to prevent re-import.
- Inject modelContainer into SwiftUI environment in IYmtgApp.

Image storage: Documents/UserContent/ subfolder (blueprint requirement)
- ImageManager.dir now targets iCloud Documents/UserContent/ (or local equiv).
- migrateImagesToUserContent() moves existing JPGs to the new subfolder on
  first launch; called during the SwiftData migration.

Firebase: demoted to optional manual backup (metadata only, no images)
- Remove all automatic CloudEngine.save/delete/batchUpdatePrices calls from
  CollectionViewModel mutations.
- Add backupAllToFirebase() for user-triggered metadata sync.
- Add isFirebaseBackupEnabled to AppConfig (default false).
- Add Cloud Backup section in Library settings with iCloud vs Firebase
  explanation and "Backup Metadata to Firebase Now" button.

Also: full modular refactor (Data/, Features/, Services/ directories) and
README updated with CloudKit setup steps and revised release checklist.

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

IYmtg_App_iOS/Services/CoreML/ConditionEngine.swift

@@ -0,0 +1,50 @@
+import Vision
+import CoreML
+import UIKit
+
+struct DamageObservation: Identifiable, Sendable {
+    let id = UUID()
+    let type: String
+    let rect: CGRect
+    let confidence: Float
+}
+
+// MARK: - CONDITION ENGINE
+class ConditionEngine {
+    enum Severity: Int { case minor = 1; case critical = 10 }
+
+    static var model: VNCoreMLModel? = {
+        guard AppConfig.enableConditionGrading else { return nil }
+        return ModelManager.shared.getModel(name: "IYmtgConditionClassifier")
+    }()
+
+    static func getSeverity(for type: String) -> Severity {
+        return (type == "Inking" || type == "Rips" || type == "WaterDamage") ? .critical : .minor
+    }
+
+    static func detectDamage(image: CGImage, orientation: CGImagePropertyOrientation = .up) -> [DamageObservation] {
+        guard let model = model else { return [] }
+        let request = VNCoreMLRequest(model: model)
+        request.imageCropAndScaleOption = .scaleFill
+        let handler = VNImageRequestHandler(cgImage: image, orientation: orientation, options: [:])
+        do {
+            try handler.perform([request])
+            guard let results = request.results as? [VNRecognizedObjectObservation] else { return [] }
+            return results.filter { $0.confidence > 0.7 }.map { obs in
+                DamageObservation(type: obs.labels.first?.identifier ?? "Unknown", rect: obs.boundingBox, confidence: obs.confidence)
+            }
+        } catch { return [] }
+    }
+
+    static func overallGrade(damages: [DamageObservation]) -> String {
+        if model == nil && damages.isEmpty { return "Ungraded" }
+        var score = 0
+        for d in damages {
+            if getSeverity(for: d.type) == .critical { return "Damaged" }
+            score += 1
+        }
+        if score == 0 { return "Near Mint (NM)" }
+        if score <= 2 { return "Excellent (EX)" }
+        return "Played (PL)"
+    }
+}