Deep-review round 1 of E22.
- After a 429 the stream sent one POST per new event while a full batch
waited; it now stays quiet for 15 s. Past the queue cap the oldest
events go, as the comment always said, a refused batch included.
- A batch refused after the level was lowered came back into the queue
of a later consent in the same tab; each consent is its own session.
- A `me` fetch that left before a level or preference change could put the
old value back for up to a minute. `updateMeCache` writes the cache and
cancels that fetch; usePref goes through it too.
- The consent box's buttons and "revert now" took the focus with them to
<body>; it returns to the level picker. Watched until the button is
gone — in Chrome the saved level arrives in two renders, and a one-shot
check spent itself on the first (jsdom never showed it).
- The countdown line is no longer a live region re-read every minute.
- "Saját napló" rows were keyed by index on a newest-first list, so every
new event remounted every row and dropped the focus off a row button.