Failures and events go out without a private feed's key (#238)

A fetch that failed logged reqwest's words, which name the whole address: Patreon's auth key
went to Loki on 2026-10-15, and, since scan events go to every open page, to everyone's
browser too. #225 had taken queries out of the traces' address fields only.

Every event is redacted where it is emitted, for the log, the live stream and a terminal
alike: address fields lose their query and password, and so does any address in an error's
words (feed::redact_text). The artwork proxy's warnings and the directory's failed checks
the same. The error kept on the feed, shown to its own subscribers, keeps the detail.

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

crates/directory/CHANGELOG.md

@@ -10,6 +10,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Security
+
+- A failed feed check is logged without its address's query or password (#238).
+
 ### Changed
 
 - The directory checks five feeds at a time, so a publisher that does not answer no longer holds up the rest of its round (#227).