Follow-up to #22208, which bounded the index table but left the frame
size itself unbounded - readBuffer and zlibBuffer are sized straight
from it, so a 96-byte header could still ask for a couple of gigabytes.
Harmless enough on 64-bit, where the pages never get touched, but a
32-bit build would just fail the allocation.
Real images use 2KB to 64KB frames, so 16MB leaves plenty of headroom.
All 19 CSOs I have on hand still load.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JvJR8oJNSCimCM9KXVLjfq