- flood retransmit jitter now capped at min(2000ms, 6·airtime) instead of
fixed 2000ms — spreads tighter at SF7, unchanged at SF8
- reactive per-dupe backoff cap now min(2000ms, 12·airtime), keeps
semantic of "push past ~12 relay slots"
- contention ring 16 → 24 for 50-neighbor hilltops
- companions passively track heard floods (warms EMA without forwarding)
and spread their own TX by up to min(1000ms, 3·airtime), hopefully
fixing repeaters missing companion's first transmission
config cleanup:
- move BLE TX buffer bumps (ACL_TX=12 etc.) from zephcore_common.conf to
esp32_common.conf — the Espressif blob needs them, nRF doesn't, and
the bumps were overflowing nRF52840 RAM
- remove CONFIG_ZEPHCORE_MAX_CONTACTS=510 overrides from 5 nRF52840
companion boards; Kconfig default of 350 fits with comfortable margin
(wio prod: 91% → 79% RAM)