perf: resize screenshots to 2x display size for major byte savings

Resized all iPhone screenshots from 1320×2868 to 416×904 (2× the 208×352
display size) and tvOS from 1920×1080 to 640×360 (2× the 320×180 display).
Re-encoded at WebP q80-82.

Before → After:
  iphone1-library:  343KB → 71KB  (-79%)
  iphone2-settings:  94KB → 23KB  (-76%)
  iphone3-emu:       92KB → 16KB  (-83%)
  tvos-library:     248KB → 49KB  (-80%)
  tvos-cheats:      130KB → 29KB  (-78%)
  Total savings: ~702KB

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: JoeMatt