types: ty 0.0.61 flags read-only shortcut_mode assignment, blocks python-deps bump (PR #120)

[millsmillsymills]

Dependabot PR #120 (fastmcp 3.4.4, pytest 9.1.1, hypothesis 6.158.0, ruff 0.15.22, ty 0.0.42 -> 0.0.61) fails the types check with one diagnostic:

error[invalid-assignment]: Property \shortcut_mode` defined in `ShortcutConfig` is read-only`

ty 0.0.61 enforces read-only property semantics that 0.0.42 missed. Fix the assignment site (or make the property writable if that is the intended contract), then merge #120. All other checks on #120 pass, including security.