feat: add screen recordings filter, exclude by default

Screen recordings are videos captured by iOS screen recording and are
almost never wanted in a photo backup. They are now excluded from all
counts and backup queues unless explicitly enabled.

Changes:
- BackupFilter.includeScreenRecordings (default: false) added
- PHAssetMediaSubtype.videoScreenRecording predicate applied in both
  fetchAssets() and fetchResultForReconciliation() — excluded at the
  PHFetchRequest level before enumeration
- LocalPhotoIndex.Record.isScreenRecording populated via makeRecord()
  so the fast-path countSafe/count also respects the toggle
- LocalPhotoIndex.passes() checks includeScreenRecordings
- Settings "Screen Recordings" toggle added below Screenshots

This also resolves the transient count flash: screen recordings were
being included in the "need backup" tally on the initial fast-path
reconcile, then dropping when the filter was fully applied.

Co-Authored-By: Kutesir <kutesir@provoc.ug>
Co-Authored-By: Sentry <sentry@provoc.ug>

Core/Protocols/PhotoLibraryProtocol.swift

@@ -11,6 +11,7 @@ struct PhotoAsset: Sendable {
     let duration: TimeInterval
     let isScreenshot: Bool
     let isRAW: Bool
+    let isScreenRecording: Bool
 }
 
 protocol PhotoLibraryProtocol: AnyObject {
@@ -26,4 +27,5 @@ struct BackupFilter: Codable, Sendable, Equatable {
     var includeScreenshots: Bool = false
     var includeRAW: Bool = false
     var newFilesOnly: Bool = true
+    var includeScreenRecordings: Bool = false
 }