push_post_to_client sent posts as TXT_TYPE_SIGNED_PLAIN (plaintext =
timestamp + flags + author_prefix + text) but computed its expected ACK
over the plain-DM span (timestamp + attempt byte + text). Signed-plain
receivers (firmware BaseChatMesh::onPeerDataRecv, and openhop_core's
text handler since it gained signed-message ACKs) reply with
sha256(decrypted[0 : 9 + strlen(text)] || client_pubkey)[:4], so the
server never recognized any push ACK: every push timed out and the same
posts were re-pushed forever (issue #286's repeating 'Push timed out'
log and duplicate unread floods).
Hash the exact plaintext span that is encrypted and sent, plus the
client pubkey. Verified against openhop_core's TextMessageHandler: the
ACK it emits for a pushed post now matches the stored pending_ack_crc.
Fixes#286
agessaman
9c6ea0151e