fix(uds-auth): keep sessions until manual sign-out; refresh expired UAC tokens by QR (0.3.20)

Users were asked to sign in again every ~30 minutes, even while active.

Session lifetime
- Browser: UDS_SESSION kept its login-time Max-Age and was never re-issued,
  so the cookie vanished 30 min after login. Re-issue it on use (throttled
  by slidingInterval).
- Desktop: remote.mux WS traffic never passed the HTTP auth middleware, so
  the idle TTL never slid. assertPrincipalLive now reports activity and
  slides the session and the account's bridges (throttled).
- New setting sessionIdleTimeoutHours (Settings page + config). Default 0 =
  no automatic sign-out; only a manual sign-out ends a session, so
  conversations and night-time cron are never cut off. 0.5-168 enables an
  idle timeout with the 7-day cap. The TTL is read live.
- Stores support long TTLs: the absolute cap follows the TTL, older 7-day
  sessions are lifted on activity, and expiry timers re-arm instead of
  overflowing setTimeout (~24.8 days).

UAC token check
- Every 2 hours (and 1 min after start) each QR session's token is checked
  against icenterapi. A rejected token is only flagged, never a sign-out.
  Network errors, 5xx and bad JSON keep the previous verdict (the old 6h
  check revoked all of an account's sessions on any failure, including
  outages).
- GET /uds-auth/session-status (non-sliding) returns alive + tokenValid.
  The client probes it every minute and on focus: a gone session signs the
  UI out with a notice; a rejected token opens a refresh QR once.
- Scanning in refresh mode writes the new token into every live session of
  the account and the skill credential cache in place: no new session, no
  reload. Other accounts are rejected (token_refresh_emp_mismatch).

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

uds-auth/package.json

@@ -1,6 +1,6 @@
 {
   "name": "uds-auth",
-  "version": "0.3.19",
+  "version": "0.3.20",
   "description": "UDS authentication plugin for DeepSeek Harness — trusted single-instance access control (not strong multi-tenant isolation)",
   "type": "module",
   "main": "lib/index.js",