Remove STIOHID support and size markers with UITouch.majorRadius

[cysp]

Why

STIOHID was an optional compile-time path. With its headers present, STTouchDisplay used private UIEvent/UITouch selectors and assumed an IOHID event object layout reconstructed in 2014; without them, it used fixed marker geometry. In an iOS 27 simulator probe, IOHIDEventGetType(root) returned digitizer type 11, while the old struct read type 1 from the same event. The reader exited at its type check and used its fixed-size fallback even with the headers present. Behavior on a physical iPhone has not been verified.

Behavior change

• Remove the conditional STIOHID reader and its obsolete header search paths. STIOHID headers no longer change how the library builds or renders markers.
• Scale both marker axes uniformly with public UITouch.majorRadius, relative to the existing 5-point reference; use the default size for a nonpositive radius.
• Stop rendering contact ellipses and rotation. The README describes the marker as an approximation of touch contact.
• Verify 2× scale at a 10-point radius and a return to the default size when a moving touch reports zero.

Validation

• Local Xcode 27: Objective-C formatting, Release demo build, five library unit tests, the demo UI test, and both static analyzers passed.
• Xcode 26 CI passed formatting, library and demo builds, unit and UI tests, and both static analyzers on the rewritten commit.
• Simulator tests verify marker behavior, not physical finger-contact geometry.