Private-server headroom over any pipeline PNG. The 8-min
auto-unready warning now mirrors the 10-min action guard: no toast
when self isn't ready, since there's nothing to lose.
64 KiB rejected normal 128px PNGs. 128 KiB fits any 128x128 PNG
(raw <= 64 KiB, worst-case base64 ~95 KiB chars) while still
bounding abuse. PNG kept for transparency. Pipeline now measures
the encoded base64 against RelayConstants (was checking the wrong
variable with its own 512 KiB limit) and drops dead crop code.
Server policy, still v4. Trade noted: avatars ride the 1 Hz room
broadcast, uplink scales with cap; hash-reference follow-up later.
foxyz