Fixes #29 — Delete downloaded video inline on the guide detail view

The middle button in the Stream/Download/Play row now cycles through the
full download lifecycle instead of ending at a disabled "Downloaded"
checkmark. Once a video is on disk the button becomes a red, destructive
"Delete" with a trash icon; tapping presents a confirmation dialog, and
confirming removes the file + SwiftData row, flipping the button back to
"Download" and disabling Play.

Settings → Downloaded Videos retains the swipe-delete and "Delete all"
affordances for bulk management.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Conjuga/Conjuga/Views/Guide/VideoActionsView.swift

@@ -20,6 +20,7 @@ struct VideoActionsButtonRow: View {
     @State private var isDownloaded: Bool
     @State private var playerVideoId: String?
     @State private var downloadError: String?
+    @State private var confirmDelete: Bool = false
 
     init(video: YouTubeVideoStore.VideoEntry) {
         self.video = video
@@ -64,6 +65,19 @@ struct VideoActionsButtonRow: View {
         } message: {
             Text(downloadError ?? "")
         }
+        .confirmationDialog(
+            "Delete this downloaded video?",
+            isPresented: $confirmDelete,
+            titleVisibility: .visible
+        ) {
+            Button("Delete", role: .destructive) {
+                downloadService.delete(videoId: video.videoId, modelContext: modelContext)
+                isDownloaded = false
+            }
+            Button("Cancel", role: .cancel) {}
+        } message: {
+            Text("You can re-download it at any time.")
+        }
         .onAppear {
             // Refresh on appear in case the user deleted the file via Settings.
             isDownloaded = VideoDownloadService.isDownloaded(videoId: video.videoId)
@@ -88,29 +102,42 @@ struct VideoActionsButtonRow: View {
 
     @ViewBuilder
     private var downloadButton: some View {
-        Button {
-            Task { await startDownload() }
-        } label: {
-            Group {
-                if let progress = activeProgress {
-                    HStack(spacing: 6) {
-                        ProgressView(value: progress)
-                            .frame(width: 40)
-                        Text("\(Int(progress * 100))%")
-                            .font(.caption.monospacedDigit())
-                    }
-                } else if isDownloaded {
-                    Label("Downloaded", systemImage: "checkmark.circle.fill")
-                } else {
-                    Label("Download", systemImage: "arrow.down.to.line")
+        // Single slot whose role flips through the download lifecycle:
+        // Download → progress (disabled) → Delete.
+        if isDownloading, let progress = activeProgress {
+            Button {} label: {
+                HStack(spacing: 6) {
+                    ProgressView(value: progress).frame(width: 40)
+                    Text("\(Int(progress * 100))%")
+                        .font(.caption.monospacedDigit())
                 }
+                .frame(maxWidth: .infinity)
             }
-            .frame(maxWidth: .infinity)
+            .buttonStyle(.bordered)
+            .tint(.blue)
+            .controlSize(.large)
+            .disabled(true)
+        } else if isDownloaded {
+            Button(role: .destructive) {
+                confirmDelete = true
+            } label: {
+                Label("Delete", systemImage: "trash")
+                    .frame(maxWidth: .infinity)
+            }
+            .buttonStyle(.bordered)
+            .tint(.red)
+            .controlSize(.large)
+        } else {
+            Button {
+                Task { await startDownload() }
+            } label: {
+                Label("Download", systemImage: "arrow.down.to.line")
+                    .frame(maxWidth: .infinity)
+            }
+            .buttonStyle(.bordered)
+            .tint(.blue)
+            .controlSize(.large)
         }
-        .buttonStyle(.bordered)
-        .tint(.blue)
-        .controlSize(.large)
-        .disabled(isDownloaded || isDownloading)
     }
 
     private var playButton: some View {