Add swipe actions: left to save, right to share + mark read

- Swipe left bookmarks a story (toggle) into the Saved tab; swipe right opens
  the iOS share sheet and marks the story read.
- New SavedStory SwiftData model; Saved tab now lists explicit bookmarks
  instead of the whole offline cache.
- Convert the feed to a styled List (native swipeActions require it), keeping
  the flat look, pull-to-refresh, and infinite scroll. Add a ShareSheet wrapper.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Jarvis/Views/SecondaryTabs.swift

@@ -86,9 +86,14 @@ struct SavedView: View {
     @Query private var cachedStories: [CachedStory]
     @Query private var cachedArticles: [CachedArticle]
     @Query private var readStories: [ReadStory]
+    @Query private var savedStories: [SavedStory]
 
     private var stories: [StorySummary] {
-        cachedStories.map(StorySummary.init(cached:)).sorted(by: StorySummary.feedOrder)
+        let savedIds = Set(savedStories.map(\.id))
+        return cachedStories
+            .filter { savedIds.contains($0.id) }
+            .map(StorySummary.init(cached:))
+            .sorted(by: StorySummary.feedOrder)
     }
 
     var body: some View {
@@ -96,15 +101,18 @@ struct SavedView: View {
             ZStack {
                 Color.black.ignoresSafeArea()
                 VStack(spacing: 0) {
-                    TabHeader(title: "Saved · offline")
+                    TabHeader(title: "Saved")
                     Divider().overlay(Palette.hairline)
                     if stories.isEmpty {
                         VStack(spacing: 12) {
                             Image(systemName: "bookmark")
                                 .font(.system(size: 28)).foregroundStyle(Color(hex: "333333"))
-                            Text("Nothing cached yet")
+                            Text("Nothing saved yet")
                                 .font(.system(size: 14, weight: .bold))
                                 .foregroundStyle(Color(hex: "555555"))
+                            Text("Swipe a story left to save it")
+                                .font(.system(size: 12))
+                                .foregroundStyle(Color(hex: "444444"))
                         }
                         .frame(maxWidth: .infinity, maxHeight: .infinity)
                     } else {