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/components/Feed.tsx

@@ -37,6 +37,7 @@ import {
 } from "../lib/feedSort";
 import { type SortOption, type SortState } from "../lib/columnSort";
 import { usePref } from "../lib/usePref";
+import { SHOW_IDS } from "./feedFiltersInit";
 import { FEED_VIEWS, type FeedView } from "../lib/feedView";
 import { clearedFilters, useActiveFilters } from "../lib/useActiveFilters";
 import ActiveFilterChips from "./ActiveFilterChips";
@@ -64,7 +65,6 @@ const PAGE = 60;
 
 // The "Show" view filter, content-type filter and ordering live in the feed toolbar
 // (above the cards), not the filter sidebar.
-const SHOW_IDS = ["unwatched", "in_progress", "all", "watched", "hidden"];
 const CONTENT = [
   { key: "includeNormal", label: "sidebar.content.normal" },
   { key: "includeShorts", label: "sidebar.content.shorts" },