Add YouTrack pull/push sync with project settings and time tracking.

Wire manual Y menu and CLI sync for issues and work items, persist
per-project credentials, and keep local edits until an explicit push.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/ticket/store.go

@@ -7,6 +7,9 @@ type Store interface {
 	Get(id string) (Ticket, error)
 	Create(t Ticket) (Ticket, error)
 	Update(t Ticket) error
+	// MarkSynced sets SyncedAt to the ticket's current UpdatedAt without
+	// bumping UpdatedAt (so NeedsPush becomes false after a remote sync).
+	MarkSynced(id string) error
 	Move(id, toProjectID string) (Ticket, error)
 	Delete(id string) error
 }