feat(intents): onscreen entity annotations + App Intents tests

- bookmarkOnscreen(_:) publishes the viewed bookmark as the on-screen
  entity (NSUserActivity.appEntityIdentifier) so Siri can resolve "this"
  / "summarize this one"; applied to the BrowserView sheets in
  BookmarksView and SearchView
- Add MarksTests (XCTest) covering entity mapping, EntityIdentifier,
  IntentRouter, and the real perform() of SearchMarksIntent and
  OpenBookmarkIntent; wired into the Marks scheme test phase

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

MarksTests/AppIntentsTests.swift

@@ -0,0 +1,107 @@
+import XCTest
+import AppIntents
+@testable import Marks
+
+/// Tests for the App Intents layer.
+///
+/// Note: WWDC26's dedicated `AppIntentsTesting` framework (out-of-process
+/// `IntentDefinitions(bundleIdentifier:)` / `.run()`) is not present in this
+/// Xcode, so these are standard XCTest cases. They work because Marks has no
+/// AppIntents extension — intents run in the app process, so `perform()` can be
+/// called directly and asserted against `IntentRouter`.
+final class AppIntentsTests: XCTestCase {
+
+    private func sampleBookmark(
+        id: Int = 42,
+        url: String = "https://example.com/article",
+        title: String = "Concurrency in Swift",
+        tags: [String] = ["swift", "concurrency"],
+        unread: Bool = true,
+        aiSummary: String? = "A short summary."
+    ) -> Bookmark {
+        Bookmark(
+            id: id, url: url, title: title, description: "desc",
+            tagNames: tags, dateAdded: Date(), dateModified: Date(),
+            isArchived: false, unread: unread, shared: false,
+            websiteTitle: nil, websiteDescription: nil,
+            faviconUrl: nil, previewImageUrl: nil,
+            aiSummary: aiSummary, aiTags: nil
+        )
+    }
+
+    // MARK: - Entity mapping
+
+    func testEntityMapsFromBookmark() {
+        let entity = BookmarkEntity(from: sampleBookmark())
+        XCTAssertEqual(entity.id, 42)
+        XCTAssertEqual(entity.title, "Concurrency in Swift")
+        XCTAssertEqual(entity.url, URL(string: "https://example.com/article"))
+        XCTAssertEqual(entity.host, "example.com")
+        XCTAssertEqual(entity.tags, ["swift", "concurrency"])
+        XCTAssertTrue(entity.unread)
+        XCTAssertEqual(entity.summary, "A short summary.")
+    }
+
+    func testEntityUsesDisplayTitleFallback() {
+        // empty title → falls back to url (Bookmark.displayTitle)
+        let entity = BookmarkEntity(from: sampleBookmark(title: ""))
+        XCTAssertFalse(entity.title.isEmpty)
+    }
+
+    func testMakeBookmarkRoundTripsCoreFields() {
+        let entity = BookmarkEntity(from: sampleBookmark())
+        let back = entity.makeBookmark()
+        XCTAssertEqual(back.id, 42)
+        XCTAssertEqual(back.url, "https://example.com/article")
+        XCTAssertEqual(back.tagNames, ["swift", "concurrency"])
+    }
+
+    func testEntityIdentifierEncodesServerId() {
+        let entity = BookmarkEntity(from: sampleBookmark(id: 7))
+        let eid = EntityIdentifier(for: entity)
+        XCTAssertEqual(eid.identifier, "7")
+        XCTAssertTrue(eid.entityType == BookmarkEntity.self)
+    }
+
+    // MARK: - Router
+
+    @MainActor
+    func testRouterSearch() {
+        IntentRouter.shared.searchRequest = nil
+        IntentRouter.shared.search("hello")
+        XCTAssertEqual(IntentRouter.shared.searchRequest, "hello")
+    }
+
+    @MainActor
+    func testRouterOpenBookmark() {
+        IntentRouter.shared.openBookmarkURL = nil
+        IntentRouter.shared.openBookmark(url: "https://example.com")
+        XCTAssertEqual(IntentRouter.shared.openBookmarkURL, "https://example.com")
+    }
+
+    // MARK: - Intent perform() wiring (no network)
+
+    @MainActor
+    func testSearchIntentRoutesCriteriaTerm() async throws {
+        IntentRouter.shared.searchRequest = nil
+        let intent = SearchMarksIntent()
+        intent.criteria = StringSearchCriteria(term: "graphql")
+        _ = try await intent.perform()
+        XCTAssertEqual(IntentRouter.shared.searchRequest, "graphql")
+    }
+
+    @MainActor
+    func testOpenIntentRoutesURL() async throws {
+        IntentRouter.shared.openBookmarkURL = nil
+        let intent = OpenBookmarkIntent()
+        intent.target = BookmarkEntity(from: sampleBookmark())
+        _ = try await intent.perform()
+        XCTAssertEqual(IntentRouter.shared.openBookmarkURL, "https://example.com/article")
+    }
+
+    // MARK: - App Shortcuts
+
+    func testAppShortcutsAreRegistered() {
+        XCTAssertGreaterThanOrEqual(MarksShortcuts.appShortcuts.count, 4)
+    }
+}