fix: renew config message TTLs at most once an hour per swarm

[mpretty-cyro]

Every poll asked the swarm to extend the TTL of every active config message. That is a write on every storage node holding those messages, every few seconds, from every client, and service nodes see real disk I/O from it. The extension goes to weeks from now, so doing it once an hour loses nothing.

The change

A poll now skips the config TTL extension for a swarm whose last extension succeeded within the last hour.

• Per swarm. The user swarm and each group swarm have their own cooldown, so one group's renewal never suppresses another's or the user's own.
• Success only. A failed extension leaves the cooldown untouched, so the next poll retries it. A failure that started the cooldown would leave the configs un-renewed while looking handled, and repeated failures could let them age out of the swarm.
• In memory, one hour, constant. No persistence or migration. A restart re-arms it, so the first poll after launch always extends.
• A throttled poll sends no expire request at all, rather than sending one and ignoring the answer.

Disappearing-message expiry uses a separate path and is unchanged.

Desktop specifics

• configTtlExtensionThrottle.ts holds a module-level per-swarm map.
• retrieveNextMessagesNoRetries decides whether to pass configHashesToBump on to buildRetrieveRequest, and records success only when the expire sub-result (last in the batch, when present) returns 200.
• Timing uses Date.now(), since this is a local interval rather than a comparison with a network value. A clock moved backwards counts as due.

Verification

configTtlExtensionThrottle_test.ts, 6 tests through retrieveNextMessagesNoRetries with BatchRequests.doUnsignedSnodeBatchRequestNoRetries stubbed, counting the batches that actually contain an expire sub-request. Covered: two polls inside the window send one; a poll after the window sends another; a 500 or a rejected batch doesn't start the cooldown; a backwards clock; per-swarm independence. Existing buildRetrieveRequest tests unchanged. tsc clean; prettier and eslint clean on the touched files. Three separate mutations (record regardless of code, drop the gate, drop the backwards-clock guard) each turn the expected tests red.

Same change in the other clients

• Renew config message TTLs at most once an hour per swarm session-ios#796
• Renew config message TTLs at most once an hour per swarm session-android#2225

[Bilb]

lgtm

[Bilb]

LGTM