putMutableItem
Store or update a mutable item, the port of put_mutable_item. The key is MutableItem.target (= SHA-1(public key ‖ salt)). If a slot already exists, the new item replaces it only when its sequence number is strictly greater (if (item.seq < seq)), so older writes can never clobber newer ones; either way the last-seen stamp is refreshed. A new slot is dropped when the table is full (see putImmutableItem on eviction).
The item must already be signed and verified. MutableItem.verify is the caller's responsibility (the node layer rejects bad signatures before calling this), mirroring libtorrent verifying in incoming_request before put_mutable_item.
Return
true if the item was inserted or replaced; false if an equal/older sequence number left the stored item unchanged or the table was full.
Parameters
current time in epoch-seconds (the item's last-seen stamp).