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/MarksAppIntents.swift

@@ -0,0 +1,177 @@
+import Foundation
+import AppIntents
+
+// MARK: - Open
+
+/// Opens a bookmark in the in-app browser. Conforms to `OpenIntent` — the
+/// system-blessed "open" type Siri understands. (iOS 26 has no separate
+/// `system.open` App Schema; `OpenIntent` with an `AppEntity` target *is* the
+/// supported mechanism, so no schema macro is needed here.)
+struct OpenBookmarkIntent: OpenIntent {
+    static let title: LocalizedStringResource = "Open Bookmark"
+    static let openAppWhenRun = true
+
+    @Parameter(title: "Bookmark")
+    var target: BookmarkEntity
+
+    @MainActor
+    func perform() async throws -> some IntentResult {
+        IntentRouter.shared.openBookmark(url: target.url.absoluteString)
+        return .result()
+    }
+}
+
+// MARK: - Search
+
+/// Searches Marks and shows the results in the app's search tab.
+///
+/// Conforms to the formal `system.search` App Schema (`ShowInAppSearchResultsIntent`),
+/// which is what makes it executable by conversational Siri / Apple Intelligence:
+/// Siri hands over the spoken term as `criteria` and the app re-runs it in its
+/// own search UI. `searchScopes` defaults to `[.general]` for string criteria.
+@AppIntent(schema: .system.search)
+struct SearchMarksIntent {
+    static let title: LocalizedStringResource = "Search Marks"
+    static let description = IntentDescription("Search your Marks bookmarks.")
+
+    @Parameter(title: "Search", requestValueDialog: "What do you want to search for?")
+    var criteria: StringSearchCriteria
+
+    @MainActor
+    func perform() async throws -> some IntentResult {
+        IntentRouter.shared.search(criteria.term)
+        return .result()
+    }
+}
+
+// MARK: - Add
+
+/// Saves a link to Marks without opening the app. Mirrors the Share Extension's
+/// headless save, but goes through the typed `LinkdingAPI`.
+struct AddBookmarkIntent: AppIntent {
+    static let title: LocalizedStringResource = "Add Bookmark to Marks"
+    static let description = IntentDescription("Save a link to your Marks bookmarks.")
+    static let openAppWhenRun = false
+
+    @Parameter(title: "URL")
+    var url: URL
+
+    @Parameter(title: "Title")
+    var name: String?
+
+    @Parameter(title: "Tags")
+    var tags: [String]?
+
+    static var parameterSummary: some ParameterSummary {
+        Summary("Add \(\.$url) to Marks") {
+            \.$name
+            \.$tags
+        }
+    }
+
+    func perform() async throws -> some IntentResult & ReturnsValue<BookmarkEntity> & ProvidesDialog & ShowsSnippetView {
+        let api = try MarksIntent.api()
+        let create = BookmarkCreate(
+            url: url.absoluteString,
+            title: name ?? "",
+            tagNames: tags ?? [],
+            isArchived: false,
+            unread: true,
+            shared: false
+        )
+        let bookmark = try await api.createBookmark(create)
+        let entity = BookmarkEntity(from: bookmark)
+        MarksIntent.refreshWidgets(adding: bookmark)
+        return .result(
+            value: entity,
+            dialog: IntentDialog("Saved \(entity.title) to Marks."),
+            view: BookmarkSnippetView(entity: entity)
+        )
+    }
+}
+
+// MARK: - Show unread
+
+/// Returns the user's unread bookmarks — "what's unread in Marks?"
+struct ShowUnreadIntent: AppIntent {
+    static let title: LocalizedStringResource = "Show Unread Bookmarks"
+    static let description = IntentDescription("List the bookmarks you haven't read yet.")
+
+    func perform() async throws -> some IntentResult & ReturnsValue<[BookmarkEntity]> & ProvidesDialog {
+        let api = try MarksIntent.api()
+        let response = try await api.fetchBookmarks(limit: 10, unread: true)
+        let entities = response.results.map(BookmarkEntity.init(from:))
+        let dialog: IntentDialog = entities.isEmpty
+            ? "You have no unread bookmarks."
+            : "You have \(entities.count) unread bookmark\(entities.count == 1 ? "" : "s")."
+        return .result(value: entities, dialog: dialog)
+    }
+}
+
+// MARK: - Summarize (AI)
+
+/// Produces an AI summary of a bookmark via the bundled ClaudeService.
+struct SummarizeBookmarkIntent: AppIntent {
+    static let title: LocalizedStringResource = "Summarize Bookmark"
+    static let description = IntentDescription("Get an AI summary of a saved bookmark.")
+
+    @Parameter(title: "Bookmark")
+    var target: BookmarkEntity
+
+    static var parameterSummary: some ParameterSummary {
+        Summary("Summarize \(\.$target)")
+    }
+
+    func perform() async throws -> some IntentResult & ReturnsValue<String> & ProvidesDialog & ShowsSnippetView {
+        let claude = ClaudeService()
+        let (summary, _) = try await claude.enrich(bookmark: target.makeBookmark())
+        return .result(
+            value: summary,
+            dialog: IntentDialog("\(summary)"),
+            view: SummarySnippetView(title: target.title, host: target.host, summary: summary)
+        )
+    }
+}
+
+// MARK: - App Shortcuts
+
+struct MarksShortcuts: AppShortcutsProvider {
+    static var appShortcuts: [AppShortcut] {
+        AppShortcut(
+            intent: AddBookmarkIntent(),
+            phrases: [
+                "Add a bookmark to \(.applicationName)",
+                "Save this link to \(.applicationName)"
+            ],
+            shortTitle: "Add Bookmark",
+            systemImageName: "bookmark"
+        )
+        AppShortcut(
+            intent: SearchMarksIntent(),
+            phrases: [
+                "Search \(.applicationName)",
+                "Search my bookmarks in \(.applicationName)"
+            ],
+            shortTitle: "Search",
+            systemImageName: "magnifyingglass"
+        )
+        AppShortcut(
+            intent: ShowUnreadIntent(),
+            phrases: [
+                "Show unread in \(.applicationName)",
+                "What's unread in \(.applicationName)"
+            ],
+            shortTitle: "Unread",
+            systemImageName: "envelope.badge"
+        )
+        AppShortcut(
+            intent: SummarizeBookmarkIntent(),
+            phrases: [
+                "Summarize a bookmark in \(.applicationName)",
+                "Summarize this with \(.applicationName)"
+            ],
+            shortTitle: "Summarize",
+            systemImageName: "sparkles"
+        )
+    }
+}