The directory's public pages read the list once a minute (#341)

/, /all, /search and /category are anyone's to ask for (#215), and each
called Store::list: the whole catalogue, joined with the snapshots and
grouped, on the 10-connection pool the refresher and every server's
/v1 calls share, on the Postgres that holds production ipx's database.
The pages' Cache-Control did nothing for a request with a query string
of its own, such as /search?q=<random>.

Directory::pages_list keeps the list for a minute behind a mutex held
through the read, so a burst of misses waits on one query rather than
each sending its own. Filtering and rendering still happen per request,
in memory. /v1/feeds, behind a token, still reads the database.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/directory/CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Security
 
 - HTTPS connections no longer trust certificates from emSign's distrusted intermediates, and certificate checks use constant-time comparisons: rustls-webpki, webpki-roots and ctutils are updated (#351).
+- The public pages read the list from the database at most once a minute, however many people ask. Each page asked for the whole catalogue, so a flood of requests with query strings of their own reached the database every time (#341).
 
 ## [1.3.0] - 2026-10-19