refactor(ios): gesture-response factory + performGesture wrapper in CommandExecution (#659)

Collapse the gesture-command boilerplate in the executeOnMain switch behind two seams:
- performGesture(app, idleTimeout:) -> (timing, outcome): folds measureGesture + the scroll
  idle-timeout/quiescence-skip wrap. Parameterized: touch gestures wrap (idleTimeout: true,
  default); synthesis gestures (pinch/rotate/transform) pass idleTimeout: false because
  RunnerSynthesizedGesture governs its own timing — a distinction that was previously implicit.
- gestureResponse(message:timing:frame:) over a GestureFrame (none/touch/drag): one factory for
  the success DataPayload (message + gesture timing + optional touch/drag visualization frame).

The 13 gesture cases (tap x3, tapSeries x2, longPress, drag, dragSeries, swipe, mouseClick, pinch,
rotateGesture, transformGesture) now use the seams; ~120 lines of repeated quartet (measureGesture +
idle-wrap + unsupported check + 8-field DataPayload) collapse. CommandExecution.swift 949 -> 867.

Behavior-preserving: identical outcomes, timing capture, DataPayload fields/messages, and the same
touch-wrapped vs synthesis-unwrapped distinction. No wire change (the factory emits the already
wire-locked DataPayload internally). mouseClick (throws) and swipe (returns an optional frame) keep
their bespoke measure/wrap but route the success payload through gestureResponse.

Verified: xcodebuild build-for-testing -> TEST BUILD SUCCEEDED (no warnings).

Author: thymikee