Introduces new window/view mail contracts for primitive right-clicks, bare-window right-clicks, and canvas clicks (with click coordinates), and documents these events in the API references. Adds context menu support to `TKPrimitive` via `setContextMenu()`/`contextMenu()`, including a new `ContextMenu` parser/validator that supports menu items, separators, and submenus while rejecting toggles, roles, and hotkeys. Also updates `HumanInputManager` to preserve the last successful pad-source listing when source reads fail, preventing false disconnect mail during transient read errors, with expanded tests covering the new menu/mail behavior and input edge cases.