feat(intents): add App Intents + Siri integration

Expose Marks to Siri, Spotlight, and Shortcuts via App Intents:

- BookmarkEntity (AppEntity + IndexedEntity, keyed on the Linkding
  server id) with a server-backed EntityStringQuery for live lookup
- Intents: Add, Open (OpenIntent), Search, ShowUnread, and an AI
  Summarize intent backed by ClaudeService; AppShortcutsProvider with
  spoken phrases; Siri snippet views and dialog
- SearchMarksIntent conforms to the system.search App Schema
  (@AppIntent(schema:), ShowInAppSearchResultsIntent) so it is
  executable by conversational Siri / Apple Intelligence
- IntentRouter bridges intents (run in the app process) to the SwiftUI
  scene for open/search navigation; widgets refreshed after adds
- Link AppIntents.framework so the metadata processor extracts shortcut
  phrases and validates the assistant schema

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

Marks/Intents/BookmarkEntity.swift

@@ -0,0 +1,122 @@
+import Foundation
+import AppIntents
+import CoreSpotlight
+
+/// A Linkding bookmark exposed to Siri, Spotlight, Shortcuts, and the
+/// Apple-Intelligence "Use Model" action.
+///
+/// Conforms to `IndexedEntity` so its title / description / tags become
+/// Spotlight-searchable, which is what lets Siri answer "find my bookmark
+/// about Swift concurrency". The identifier is the Linkding server id (`Int`),
+/// which is stable across devices.
+struct BookmarkEntity: AppEntity, IndexedEntity {
+    static let typeDisplayRepresentation = TypeDisplayRepresentation(name: "Bookmark")
+
+    let id: Int
+
+    @Property(title: "Title")
+    var title: String
+
+    @Property(title: "URL")
+    var url: URL
+
+    @Property(title: "Website")
+    var host: String
+
+    @Property(title: "Description")
+    var details: String
+
+    @Property(title: "Tags")
+    var tags: [String]
+
+    @Property(title: "Unread")
+    var unread: Bool
+
+    /// AI-generated summary (when one has been produced). Exposed so the
+    /// Shortcuts "Use Model" action and Siri can reason over it.
+    @Property(title: "Summary")
+    var summary: String?
+
+    static let defaultQuery = BookmarkQuery()
+
+    var displayRepresentation: DisplayRepresentation {
+        DisplayRepresentation(
+            title: "\(title)",
+            subtitle: "\(host)",
+            image: .init(systemName: "bookmark.fill")
+        )
+    }
+
+    /// Rich Spotlight attributes so semantic search has real content to match.
+    var attributeSet: CSSearchableItemAttributeSet {
+        let attrs = CSSearchableItemAttributeSet(contentType: .url)
+        attrs.title = title
+        attrs.contentDescription = details.isEmpty ? summary : details
+        attrs.keywords = tags
+        attrs.url = url
+        return attrs
+    }
+}
+
+extension BookmarkEntity {
+    init(from b: Bookmark) {
+        self.id = b.id
+        self.title = b.displayTitle
+        self.url = URL(string: b.url) ?? URL(string: "https://example.invalid")!
+        self.host = b.domain
+        self.details = b.contentExcerpt ?? ""
+        self.tags = b.tagNames
+        self.unread = b.unread
+        self.summary = b.aiSummary
+    }
+
+    /// Reconstruct a minimal `Bookmark` from the entity — enough for the
+    /// AI enrichment call, which only reads url/title/tags.
+    func makeBookmark() -> Bookmark {
+        Bookmark(
+            id: id,
+            url: url.absoluteString,
+            title: title,
+            description: details,
+            tagNames: tags,
+            dateAdded: Date(),
+            dateModified: Date(),
+            isArchived: false,
+            unread: unread,
+            shared: false,
+            websiteTitle: nil,
+            websiteDescription: nil,
+            faviconUrl: nil,
+            previewImageUrl: nil,
+            aiSummary: summary,
+            aiTags: nil
+        )
+    }
+}
+
+/// Looks bookmarks up by id and resolves free-text queries by hitting the
+/// Linkding server live — the recommended path for data that lives on a
+/// server and changes too often to pre-index.
+struct BookmarkQuery: EntityStringQuery {
+    func entities(for identifiers: [Int]) async throws -> [BookmarkEntity] {
+        let api = try MarksIntent.api()
+        // Linkding has no batch-by-id endpoint; pull a page and filter.
+        let response = try await api.fetchBookmarks(limit: 200)
+        let wanted = Set(identifiers)
+        return response.results
+            .filter { wanted.contains($0.id) }
+            .map(BookmarkEntity.init(from:))
+    }
+
+    func entities(matching string: String) async throws -> [BookmarkEntity] {
+        let api = try MarksIntent.api()
+        let response = try await api.fetchBookmarks(search: string, limit: 25)
+        return response.results.map(BookmarkEntity.init(from:))
+    }
+
+    func suggestedEntities() async throws -> [BookmarkEntity] {
+        let api = try MarksIntent.api()
+        let response = try await api.fetchBookmarks(limit: 10)
+        return response.results.map(BookmarkEntity.init(from:))
+    }
+}