Add token rotation

jarl token rotate, a Rotate button in the web UI and
POST /api/v1/tokens/{id}/rotate give a token a new secret while it keeps
its ID, name, user and grants. The old secret stops at once or after a
grace period of up to 7 days, during which jarld logs who still uses it.
A token that expires gets its lifetime again. --save writes the new
secret where the CLI got the old one (its configuration or --token @FILE),
--write FILE to any file, and --current picks the token the CLI runs
with, so a restricted token can renew itself. A restricted token can't
rotate a wider token of its user.

Also fixes token create --save for named servers, and future times
(token expiry) shown as "just now" in the web UI.

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

internal/web/static/assets/style.css

@@ -78,6 +78,7 @@ h3 { font-size: 14px; margin: 14px 0 6px; }
 .muted { color: var(--muted); }
 .small { font-size: 12px; }
 .nowrap { white-space: nowrap; }
+.warn-text { color: var(--warn); }
 .right { text-align: right; }
 .hidden { display: none !important; }