feat(ui): E31 S4a — rail rows are links, the channel page opens on unwatched, users and audit tidied

- Nav rail page rows are real links (/?page=<id>): a middle-click or
  Ctrl-click opens the page in a new tab; a plain click stays in-app.
- A fresh channel page shows the unwatched videos; a picked watch state
  is a remembered preference (channelShow).
- Users: the role, suspend and delete move into the row's one menu
  (the "…", right-click, Shift+F10); locked ones keep their reason.
- Audit log: back-to-back successful runs of one job fold into one row
  that opens to the earlier ones; a failed run reads in the danger colour.
- DESIGN.md decision log: the E31 picks.

frontend/src/lib/auditGroups.ts

@@ -0,0 +1,32 @@
+import type { AuditRow } from "./api";
+
+// The audit log's scheduler noise, folded (E31, the owner's pick): the background jobs write a row per
+// run that changed something, so an hour of "enrichment done" filled the first screen and pushed the
+// admins' own actions down. Back-to-back SUCCESSFUL runs of the same job become one row that names how
+// many there were and opens to each; a failed or skipped run is never folded — it stays a row of its
+// own, where it is seen. Rows arrive newest first; the group stands at its newest run's place.
+
+/** An audit row as the table lists it: a lone row, or the newest of a run of folded ones (`runs`, the
+ *  whole run newest first, the row itself included). */
+export type AuditListRow = AuditRow & { runs?: AuditRow[] };
+
+/** The job a row is a successful run of, or null for any other row. */
+function okRunOf(row: AuditRow): string | null {
+  if (row.action !== "job_run" || row.target_type !== "job" || !row.target_id) return null;
+  return row.after?.status === "ok" ? row.target_id : null;
+}
+
+export function foldJobRuns(rows: readonly AuditRow[]): AuditListRow[] {
+  const out: AuditListRow[] = [];
+  let head: AuditListRow | null = null;
+  for (const row of rows) {
+    const job = okRunOf(row);
+    if (job !== null && head !== null && okRunOf(head) === job) {
+      head.runs = [...(head.runs ?? [head]), row];
+      continue;
+    }
+    head = { ...row };
+    out.push(head);
+  }
+  return out;
+}