Add offline-first task-master TUI with tickets, board lists, and undo.

Charm-based CLI with JSON persistence, status/list filters, external editor editing, command-history undo/redo, and glamour markdown without AutoStyle OSC hangs.

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

internal/ticket/store.go

@@ -0,0 +1,11 @@
+package ticket
+
+// Store is the persistence interface for tickets.
+// Implementations must be safe for concurrent use.
+type Store interface {
+	List(projectID string) ([]Ticket, error)
+	Get(id string) (Ticket, error)
+	Create(t Ticket) (Ticket, error)
+	Update(t Ticket) error
+	Delete(id string) error
+}