Log failed logins and refused tokens, address first

For Guard's jarl preset and fail2ban: msg="login failed" ip=... user=...
and msg="token refused" ip=..., beside the audit records.

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

CHANGELOG.md

@@ -6,6 +6,14 @@ All notable changes to Jarl are documented here. The format follows
 
 ## [Unreleased]
 
+### Added
+
+- **Failed logins in the journal.** A failed login (a wrong password, or
+  a wrong two-factor code) and a refused API token are logged as well as
+  audited, with the address first (`msg="login failed" ip=… user=…`,
+  `msg="token refused" ip=…`), for Guard's `jarl` preset or a fail2ban
+  filter to ban such addresses (docs/operations.md).
+
 ## [0.6.3] - 2026-10-21
 
 ### Added