fix: hide notes toggle when not using Google Calendar, strengthen nil tests

Use a gated Binding so the toggle visually shows off when the event store
provider is not Google Calendar (while preserving the stored preference for
when the user switches back). Use XCTUnwrap in nil-asserting tests so a
parser regression that returns nil is caught rather than silently passing.

Author: claude

MeetingBar/UI/Views/Preferences/LinksTab.swift

@@ -58,10 +58,13 @@ struct LinksTab: View {
                     }
                 }
 
-                Toggle("preferences_services_meet_open_notes_on_join".loco(), isOn: $openGoogleMeetingNotesOnJoin)
-                    .frame(maxWidth: .infinity, alignment: .leading)
-                    .disabled(eventStoreProvider != .googleCalendar)
-                    .help("preferences_services_meet_open_notes_on_join_help".loco())
+                Toggle("preferences_services_meet_open_notes_on_join".loco(), isOn: Binding(
+                    get: { eventStoreProvider == .googleCalendar && openGoogleMeetingNotesOnJoin },
+                    set: { openGoogleMeetingNotesOnJoin = $0 }
+                ))
+                .frame(maxWidth: .infinity, alignment: .leading)
+                .disabled(eventStoreProvider != .googleCalendar)
+                .help("preferences_services_meet_open_notes_on_join_help".loco())
 
                 Picker(
                     selection: $zoomBrowser,

MeetingBarTests/GCEventStoreTests.swift

@@ -35,7 +35,7 @@ final class GCEventStoreTests: XCTestCase {
                        "https://docs.google.com/document/d/abc123/edit")
     }
 
-    func testIgnoresNonDocumentAttachment() {
+    func testIgnoresNonDocumentAttachment() throws {
         var item = baseItem()
         item["attachments"] = [
             [
@@ -46,14 +46,14 @@ final class GCEventStoreTests: XCTestCase {
             ]
         ]
 
-        let event = GCEventStore.GCParser.event(from: item, calendar: calendar)
+        let event = try XCTUnwrap(GCEventStore.GCParser.event(from: item, calendar: calendar))
 
-        XCTAssertNil(event?.meetingNotesDocLink)
+        XCTAssertNil(event.meetingNotesDocLink)
     }
 
-    func testNoAttachmentsLeavesMeetingNotesNil() {
-        let event = GCEventStore.GCParser.event(from: baseItem(), calendar: calendar)
+    func testNoAttachmentsLeavesMeetingNotesNil() throws {
+        let event = try XCTUnwrap(GCEventStore.GCParser.event(from: baseItem(), calendar: calendar))
 
-        XCTAssertNil(event?.meetingNotesDocLink)
+        XCTAssertNil(event.meetingNotesDocLink)
     }
 }