fix(speedrun): pause queue on 429/420 instead of dropping it

speedrun.com returns 429 or 420 when we ask too fast. These were
counted as errors: 3 in a row dropped both queues. Now the thread
pauses and retries the same game. Rate: 1 request per 2 s. Refs #48

readme.md

@@ -72,7 +72,9 @@ To Be Played is split into three repositories:
   least one verified run. An edition that finds nothing tries its IGDB parent game with the parent's year, else its
   name without an edition suffix. Several same-name games and no year to decide: no link. The game detail returns
   the speedrun.com link as `speedrunUrl`. speedrun.com has no Steam or IGDB link and no key, so one queue works for
-  all users, with up to 3 requests per game and 1 request per second; a result is kept 30 days. Migration V47 asks
+  all users, with up to 3 requests per game and 1 request every 2 seconds; a result is kept 30 days. A rate limit answer
+  (429 or 420) pauses the queue (its Retry-After, else 1 min doubling up to 30 min) and asks the same game again; the
+  queue is never dropped for it. Migration V47 asks
   every stored match again once at boot, behind user requests; links set by an auditor are never touched.
 - **Achievements**: after every library sync a background job fetches the achievement schema of each owned game
   and the user's unlocks of each game whose playtime changed. One Steam call per second, so user requests keep half