Make the Auth tab explain a number instead of only showing it

A low uptime figure, a refused login and a certificate that stopped
renewing all looked the same from the row: a number, with the reason
split across NPM, an Authelia config and the directory.

The why-check goes and looks — TCP to the forward target, HTTP through
the proxy, a second handshake with verification off to tell a broken
certificate from a broken service. Forward hosts are docker names that
only resolve on NPM's network, so an unresolvable one is redirected to
the container address and the substitution is reported; a check that
could not be made must never read as a check that failed.

The access simulator walks the rules the way Authelia does and shows the
ones it stepped over, reading whichever instance the chosen host points
at rather than the one conf names — there are two here.

Cert triage counts runs rather than log lines and orders by rotation
suffix rather than mtime, both of which change the answer.

Plugin/unraid/Tools/uptime_probe.php

@@ -97,10 +97,6 @@ function vv_uptime_write(array $d): bool {
     return true;
 }
 
-function vv_uptime_pct(int $up, int $total): ?float {
-    return $total > 0 ? round($up / $total * 100, 2) : null;
-}
-
 // ── Report ────────────────────────────────────────────────────────────────────
 // Anything that was not perfect over the last seven days, for the Sunday report. Prints nothing
 // and exits 0 when every domain was clean — the orchestrator's job is to be quiet on a good week,
@@ -157,14 +153,12 @@ if ($status || $events) {
     exit(0);
 }
 
-// Shared by --status, --report and the API. Buckets are keyed by time so "the last N" is a key sort, not an assumption about how many
-// samples a period should contain — a pass that did not run leaves no bucket rather than a zero.
+// Shared by --status, --report and the API, and defined once in include/auth.php so the three
+// callers cannot drift apart on what "the last N" means. Buckets are keyed by time, so it is a key
+// sort rather than an assumption about how many samples a period should contain — a pass that did
+// not run leaves no bucket rather than a zero.
 function vv_uptime_window(array $buckets, int $n): ?float {
-    if (!$buckets) return null;
-    krsort($buckets);
-    $u = $t = 0;
-    foreach (array_slice($buckets, 0, $n, true) as $b) { $u += $b['u'] ?? 0; $t += $b['t'] ?? 0; }
-    return vv_uptime_pct($u, $t);
+    return vv_auth_uptime_window($buckets, $n);
 }
 
 // ── One pass ──────────────────────────────────────────────────────────────────