Example enc4: m_iDesiredFOV (visible zoom) instead of m_flViewmodelFOV

The struct-dump diag proved the quantized substitution is correct on the wire
(m_flViewmodelFOV: count@+0x28=1, real f0=60, we write the fake) — but that
field is the gun/viewmodel FOV (own-view, influenced by the client viewmodel_fov
cvar) so it isn't visibly rendered. The visible FOV is m_iDesiredFOV
(CBasePlayerController, uint) — the field game code uses to zoom. Point enc4 at
it = every client's view zooms in, an unmistakable demo.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>