Fix backup state logic, ring colors, Already Safe invariant, and dedup

BackupJob: fix finish() — failedCount > 0 now correctly sets .failed
instead of .completed in both branches.

BackupEngine: replace filename-only fileExists check with a 3-layer
dedup strategy. For each asset: (1) check ManifestIndex by localIdentifier
O(1); (2) filename fallback for bootstrap manifests; (3) NAS fileExists
for files not yet in manifest. Never overwrite an existing NAS file.
Manifest index is built once after connect and held in a local let for
the loop — Data+BackupManifest are released immediately after.

BackupView — ring color:
  active (running/preparing/paused) → orange always
  failed → destructive
  needBackup == 0 && phoneTotal > 0 → green
  default → neutral gray
  Ring is no longer permanently green after .completed.

BackupView — CTA button:
  Default color is always black (AppTheme.ink).
  On .completed: briefly flashes green for 2.5 s then smoothly
  reverts to black. ctaFlashGreen state drives the color.

BackupView — Already Safe invariant:
  alreadySafeDisplayCount = min(base + uploadedFiles, phoneTotal)
  during active backup; min(base, phoneTotal) otherwise.
  Adding skippedFiles was removed — they are already counted in
  snapshot.alreadySafe from the last reconcile.
  notBackedUpDisplayCount is derived from alreadySafeDisplayCount to
  keep the invariant alreadySafe + needBackup == phoneTotal.

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

Services/BackupEngine.swift

@@ -73,7 +73,19 @@ final class BackupEngine: ObservableObject {
             activeTransfer = nil
         }
 
-        // 3. Start job tracking
+        // 3. Load manifest → build index (manifest Data+struct released after this block)
+        let manifestPath = "\(connection.remotePath)/\(BackupManifest.remoteFilename)"
+        let index: ManifestIndex
+        if let data = try? await transfer.downloadData(at: manifestPath),
+           let manifest = try? JSONDecoder().decode(BackupManifest.self, from: data) {
+            index = ManifestIndex(manifest: manifest)
+            logger.info("Manifest loaded — \(index.totalCount) entries, filename-only=\(index.isFilenameOnly)")
+        } else {
+            index = ManifestIndex(nasListing: [])
+            logger.info("No manifest — will check NAS file existence per asset")
+        }
+
+        // 4. Start job tracking
         job.start(totalFiles: assets.count, totalBytes: 0)
 
         var uploaded = 0
@@ -83,21 +95,40 @@ final class BackupEngine: ObservableObject {
         var speedTracker = SpeedTracker()
         var manifestEntries: [ManifestEntry] = []
 
-        // 4. Transfer loop
+        // 5. Transfer loop
         for asset in assets {
             if isCancelled { break }
             while case .paused = job.status {
                 try await Task.sleep(nanoseconds: 500_000_000)
             }
 
-            let remotePath = "\(connection.remotePath)/\(asset.filename)"
-
-            if filter.newFilesOnly, (try? await transfer.fileExists(at: remotePath)) == true {
+            // ── Primary dedup: manifest localIdentifier (O(1), no network call) ──
+            if index.matches(localIdentifier: asset.localIdentifier) {
                 job.fileCompleted(skipped: true)
                 skipped += 1
+                logger.debug("Skipped (manifest id): \(asset.filename, privacy: .public)")
                 continue
             }
 
+            // ── Filename fallback: bootstrap manifest has no localIdentifiers ──
+            if index.isFilenameOnly && index.matches(filename: asset.filename) {
+                job.fileCompleted(skipped: true)
+                skipped += 1
+                logger.debug("Skipped (manifest filename): \(asset.filename, privacy: .public)")
+                continue
+            }
+
+            // ── NAS file existence check — never overwrite ──
+            let baseRemotePath = "\(connection.remotePath)/\(asset.filename)"
+            let fileAlreadyExists = (try? await transfer.fileExists(at: baseRemotePath)) == true
+            if fileAlreadyExists {
+                job.fileCompleted(skipped: true)
+                skipped += 1
+                logger.debug("Skipped (NAS exists, no-overwrite): \(asset.filename, privacy: .public)")
+                continue
+            }
+
+            // ── Upload ──
             do {
                 let localURL = try await photoService.exportAsset(asset)
                 defer { try? FileManager.default.removeItem(at: localURL) }
@@ -105,7 +136,7 @@ final class BackupEngine: ObservableObject {
                 let fileSize = (try? localURL.resourceValues(forKeys: [.fileSizeKey]).fileSize)
                     .flatMap { Int64($0) } ?? 0
 
-                try await transfer.upload(localURL: localURL, remotePath: remotePath) { sent, total in
+                try await transfer.upload(localURL: localURL, remotePath: baseRemotePath) { sent, total in
                     let speed = speedTracker.update(bytesSent: sent)
                     Task { @MainActor [weak self] in
                         self?.job.updateProgress(
@@ -126,7 +157,7 @@ final class BackupEngine: ObservableObject {
                     filename: asset.filename,
                     creationDate: asset.creationDate,
                     fileSize: fileSize,
-                    remotePath: remotePath,
+                    remotePath: baseRemotePath,
                     uploadedAt: Date()
                 ))
             } catch {