The contract blocks vote_reserve during a halt (SystemHalted revert), but the
validator currently still runs the full handler and submits the doomed
extrinsic. During a halt that turns into a retry storm: miners re-request,
each failed reserve burns a round-trip, and the writes contend for the
hotkey's nonce/write path — starving confirm/timeout votes for in-flight swaps.

Check bounds_cache.halted() at the top of handle_swap_reserve and reject
immediately, before any provider/substrate work or extrinsic submission.
halted() fails open, so an RPC blip falls through to the contract's own
rejection rather than refusing a valid reserve.

Co-authored-by: anderdc <me@alexanderdc.com>