Dashboard: hide archived sessions from the All-sites list (hc-7vo)

Follow-up to the archive feature: archived healthchecks showed in both the
main All-sites list and the Archived section. allSitesSummary() now excludes
archived sessions from the aggregate (and from the per-site "latest session"
detail), so a site whose sessions are all archived drops off the main list
and appears only under "Archived". A site with a mix keeps its row, counting
only its live sessions. The per-site page still lists every session.

Also bumps the server version baseline in config.php.example to 0.1.8.

2 new tests (51 total).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/config.php.example

@@ -28,5 +28,5 @@ return [
     'db_pass' => 'REPLACE_WITH_DB_PASSWORD',
 
     // Server version, surfaced on GET /. Bump on deploy.
-    'version' => '0.1.0',
+    'version' => '0.1.8',
 ];

server/src/Store.php

@@ -222,10 +222,17 @@ final class Store {
     /**
      * Summary of all sites for the dashboard: one row per site_key,
      * ordered by most-recently-active first.
-     * `next_due` is taken from the most recent session, not from the most recent
-     * session that happens to have one set. If the latest visit didn't schedule a
-     * return, the site genuinely has nothing scheduled — carrying an older date
-     * forward would show a visit as overdue immediately after it was completed.
+     *
+     * Archived sessions are excluded from the aggregate, so a site whose sessions
+     * are all archived drops off this list entirely (it still shows, per session,
+     * under the dashboard's "Archived" heading). Every column — counts, latest
+     * dates, next_due — reflects only the site's non-archived sessions.
+     *
+     * `next_due` is taken from the most recent (non-archived) session, not from
+     * the most recent one that happens to have one set. If the latest visit didn't
+     * schedule a return, the site genuinely has nothing scheduled — carrying an
+     * older date forward would show a visit as overdue immediately after it was
+     * completed.
      *
      * @return array<int, array{site_key:string, total:int, finished:int, last_started_at:int, last_finished_at:int|null, last_reporting_url:string, next_due:string|null}>
      */
@@ -237,16 +244,18 @@ final class Store {
                 SUM(CASE WHEN finished_at IS NOT NULL THEN 1 ELSE 0 END) AS finished,
                 MAX(started_at)                                 AS last_started_at
              FROM healthchecks
+             WHERE archived = 0
              GROUP BY site_key
              ORDER BY MAX(updated_at) DESC'
         );
         $rows = $stmt->fetchAll();
-        // Fetch the reporting_url and finished_at from the most recent session per site.
+        // Fetch the reporting_url and finished_at from the most recent NON-archived
+        // session per site (the site is only here because it has at least one).
         $out = [];
         foreach ($rows as $r) {
             $detail = Db::pdo()->prepare(
                 'SELECT reporting_url, finished_at, next_due FROM healthchecks
-                 WHERE site_key = ? ORDER BY started_at DESC LIMIT 1'
+                 WHERE site_key = ? AND archived = 0 ORDER BY started_at DESC LIMIT 1'
             );
             $detail->execute([$r['site_key']]);
             $last = $detail->fetch() ?: [];