fix code review issues: deferral date format, storeFlags SELECT, event loop leaks, GTD selection tracking

- fix deferral resurfacing using VTODOParser.formatDateOnly instead of ISO8601 (date format mismatch)
- add SELECT mailbox before UID STORE in storeFlags (IMAP protocol requirement)
- pass credentials to SyncCoordinator so IDLE monitoring activates
- add selectedItem tracking to MailViewModel, wire List selection in GTD views
- fix startPeriodicSync to sleep-first, preventing duplicate sync on launch
- add deinit cleanup for EventLoopGroup in IMAPConnection, SMTPConnection
- use separate IMAP client for attachment downloads, avoid shared connection interference
- remove [weak self] from IMAPIdleClient actor Task to prevent orphaned connections
- fix isGTDPerspective to check selectedMailbox instead of items.isEmpty
- fix fetchBody to use complete RFC822 fetch instead of BODY[TEXT]
- reuse single IMAP connection per ActionQueue.flush() batch
- add requiresIMAP to ActionPayload for connection batching
- load task categories from label store instead of hardcoded empty array
- suppress NIOSSLHandler Sendable warnings via Package.swift unsafeFlags
- fix unused variable warnings across codebase

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Apps/MagnumOpus/ContentView.swift

@@ -111,7 +111,7 @@ struct ContentView: View {
 	@ViewBuilder
 	private var statusBanner: some View {
 		switch viewModel.syncState {
-		case .error(let message):
+		case .error(_):
 			HStack {
 				Image(systemName: "wifi.slash")
 				Text("Offline — showing cached mail")

Apps/MagnumOpus/ViewModels/MailViewModel.swift

@@ -59,6 +59,7 @@ final class MailViewModel {
 
 	var selectedPerspective: Perspective = .inbox
 	var items: [ItemSummary] = []
+	var selectedItem: ItemSummary?
 	var perspectiveCounts: [Perspective: Int] = [:]
 
 	private var imapClientProvider: (() -> IMAPClient)?
@@ -134,7 +135,15 @@ final class MailViewModel {
 			imapClient: imapClient,
 			store: mailStore,
 			actionQueue: queue,
-			taskStore: ts
+			taskStore: ts,
+			credentials: credentials,
+			imapClientProvider: {
+				IMAPClient(
+					host: capturedImapHost,
+					port: capturedImapPort,
+					credentials: capturedCredentials
+				)
+			}
 		)
 	}
 
@@ -471,7 +480,7 @@ final class MailViewModel {
 	// MARK: - GTD Triage Actions (unified items)
 
 	func deferItem(_ item: ItemSummary, until date: Date?) {
-		guard let store, let accountConfig else { return }
+		guard let store, let _ = accountConfig else { return }
 		do {
 			switch item {
 			case .email(let msg):
@@ -498,7 +507,7 @@ final class MailViewModel {
 	}
 
 	func fileItem(_ item: ItemSummary, label: LabelInfo) {
-		guard let store, let accountConfig else { return }
+		guard let store, let _ = accountConfig else { return }
 		do {
 			switch item {
 			case .email(let msg):
@@ -674,7 +683,7 @@ final class MailViewModel {
 			deferUntil: record.deferUntil.flatMap { VTODOParser.parseDate($0) },
 			createdAt: VTODOParser.parseDate(record.createdAt) ?? Date.distantPast,
 			linkedMessageId: record.linkedMessageId,
-			categories: [],
+			categories: (try? store?.labelsForItem(itemType: "task", itemId: record.id).map(\.name)) ?? [],
 			isSomeday: record.isSomeday
 		)
 	}

Apps/MagnumOpus/Views/ThreadListView.swift

@@ -8,15 +8,15 @@ struct ThreadListView: View {
 	@State var showDeferPicker = false
 	@State var showLabelPicker = false
 
-	/// Whether the current view shows a GTD perspective (vs. a raw mailbox folder)
+	/// Whether the current view shows a GTD perspective (vs. a raw mailbox folder).
+	/// Items being empty does not mean we're in folder mode — an empty GTD perspective is still GTD.
 	private var isGTDPerspective: Bool {
-		// GTD perspectives are active when items are loaded
-		!viewModel.items.isEmpty || viewModel.selectedMailbox == nil
+		viewModel.selectedMailbox == nil
 	}
 
 	var body: some View {
 		Group {
-			if !viewModel.items.isEmpty {
+			if isGTDPerspective {
 				itemListView
 			} else {
 				threadListView
@@ -52,7 +52,12 @@ struct ThreadListView: View {
 	// MARK: - Unified Item List (GTD perspectives)
 
 	private var itemListView: some View {
-		List(viewModel.items) { item in
+		List(viewModel.items, selection: Binding(
+			get: { viewModel.selectedItem?.id },
+			set: { newId in
+				viewModel.selectedItem = viewModel.items.first { $0.id == newId }
+			}
+		)) { item in
 			ItemRow(item: item)
 				.tag(item.id)
 		}
@@ -239,9 +244,11 @@ struct ThreadListView: View {
 	// MARK: - Helpers
 
 	private var selectedItemSummary: ItemSummary? {
-		// In GTD mode, use the first item (or a future selection mechanism)
-		// For now, if there's a selected thread, build the email item from it
-		if let thread = viewModel.selectedThread,
+		if let selected = viewModel.selectedItem {
+			return selected
+		}
+		// Fallback: in folder view, use selected thread
+		if let _ = viewModel.selectedThread,
 		   let msg = viewModel.messages.first {
 			return .email(msg)
 		}