d732d3bb86897cc43697d418eb589d29081ed549  WKWebView.magnification reports the pre-gesture scale while a committed transient zoom animates

Classified as not security-relevant.
Triage note: Adds committedTransientZoomScale() tracking (m_committedTransientZoomScale) so ViewGestureController::magnification() reports the committed scale between committing and applying a transient zoom, plus testing getters _minMagnification/_maxMagnification. This is a zoom-gesture correctness fix, not a memory-safety or policy bug.
This commit was flagged by the signal scorer and reviewed by AI (not a human). It is listed only so the triage is auditable; there is no root-cause analysis because this is not a vulnerability fix.

Structural signals: smartptr_member_added (+4.87), null_guard (+1.2), surgical (+1.3)