fix(reader): force menu rebuild so toggle checkmarks reflect state

Viewer Insights (and likely Subscribed/Full Width, same mechanism)
kept showing the pre-toggle checkmark in the overflow menu until the
whole view was torn down and rebuilt (navigate away and back) -
SwiftUI's macOS Menu doesn't reliably re-evaluate a Toggle's checkmark
against updated @Observable state on its own. Keying the Menu's .id()
to every toggle-backed state it displays forces a fresh rebuild
whenever any of them change.

Outpost/Features/Collections/DocumentReaderView.swift

@@ -127,6 +127,13 @@ struct DocumentReaderView: View {
                 } label: {
                     Image(systemName: "ellipsis.circle")
                 }
+                // SwiftUI's macOS `Menu` doesn't reliably re-evaluate a
+                // `Toggle`'s checkmark against updated @Observable state on
+                // its own — without a fresh `.id()` per state combination,
+                // toggling Subscribed/Viewer Insights/Full Width kept
+                // showing the pre-toggle checkmark until the whole view was
+                // torn down and rebuilt (e.g. navigating away and back).
+                .id(menuIdentity)
             }
         }
         .task { await viewModel.loadFullContent() }
@@ -205,6 +212,19 @@ struct DocumentReaderView: View {
         }
     }
 
+    /// Every toggle-backed piece of state shown as a checkmark inside
+    /// `menuContent` — see the `.id()` comment on the `Menu` above.
+    private var menuIdentity: String {
+        [
+            starStore.isStarred(documentId: viewModel.documentId),
+            viewModel.isSubscribed,
+            viewModel.isPinned,
+            viewModel.isInsightsEnabled ?? false,
+            viewModel.isFullWidth,
+            viewModel.isEditing
+        ].map(String.init).joined(separator: "-")
+    }
+
     @ViewBuilder
     private var viewerAvatars: some View {
         if !viewModel.viewers.isEmpty {