* fix(relay): stop sibling gateways answering another instance's button press
A Discord button press arrives on the passthrough plane, and the connector
fans a passthrough forward out to EVERY live gateway session of the tenant
(relayServer.routeBusMessage delivers `passthrough` via sessionsByTenant),
unlike a message, which it narrows to the admitted instance set. The prompt
went out from exactly one instance and _pending_prompts is process-local, so
every sibling gateway saw an answer for a prompt it never minted, could not
tell that from its own prompt expiring, and fell through to chat dispatch --
where the option-shaped text ("/c1") is not a real command and run.py replied
"Unknown command `/c1`". One copy per sibling, under the single real ack.
Prompt ids are now minted as `<per-process nonce>.<8 hex>`, so an answer can
be attributed to the process that minted it. A prompt answer is always
consumed, never re-dispatched as chat: a sibling's prompt and a repeat answer
are both dropped silently, and an expired prompt of our own gets a short
"no longer waiting" notice from the owning gateway only.
Ids stay inside the connector codec's contract ([A-Za-z0-9_.-], <=32 chars,
64-byte callback budget -- verified against promptCodec.ts: 52 bytes worst
case with a full-length option id). An id with no nonce segment (a prompt in
flight across an in-place upgrade) is still treated as ours.
Tests: 4 added, each verified to fail without the fix. Full relay suite green
(160 tests).
* style(tests): ruff-format the added relay prompt tests
a189286aea