feat(admin): all-podcasts view — disk-first maintenance for every feed

§0 item 8 (Phase-4 item 1 pulled forward, user directive: maintenance
tooling ships WITH the features it maintains):

- /admin/podcasts (AdminMiddleware): every feed from EVERY user via the
  RLS admin escape (first-admin identity, poller/fetcher contract) —
  feed + host, library, subscriber count/names, downloaded/total, DISK
  USAGE, last fetch. Sorted disk DESC ('what's eating the disk'),
  totals header (feeds · episodes · bytes on disk).
- Per-feed actions: Refresh · Delete files (rows → pending, disk freed;
  confirms spell out the re-materialization contract) · Remove feed
  (rows + files for everyone — the same admin delete as the detail
  page). All confirms ride the global confirm modal.
- New sqlc: ListAllPodcastFeedsAdmin (correlated aggregates),
  ResetPodcastEpisodeFileDeleted / ResetPodcastFeedFilesDeleted —
  downloaded rows reset to pending with download-derived facts cleared
  (audio_metadata, chapter_count, cover, size, mime); file_path KEPT
  (fetch-maintained layout — a re-download lands on the same path).
  file deletion via the existing DeleteFeedFiles file-removal pattern
  (episode files + .cover.jpg siblings).
- Poll upsert never touches download_state, so deleted files STAY
  deleted — a feed refresh re-lists metadata but re-materializes
  nothing (pinned by TestAdminDeleteEpisodeFiles).
- Per-episode admin delete-file: POST /feeds/:id/episodes/:eid/
  delete-file (admin) — one episode's file gone, row pending, siblings
  untouched; HX swaps the episode list. (Found while testing: the
  handler first read c.Param("id") — the FEED's uuid — instead of
  :eid; the 404 'episode not found' trail led straight to it.)
- Tests: admin sees other users' feeds + subscriber names; regular
  users 403 on page AND actions; single + feed-level deletion reset
  rows/clear facts/delete files; refresh leaves pending rows pending.
- Admin nav gains 'Podcasts' under Administration.

Wrong-gotcha note for future agents: parseUUID on c.Param('id') inside
a /feeds/:id/episodes/:eid route resolves the FEED, not the episode.

internal/services/podcast_service.go

@@ -542,6 +542,66 @@ func (s *PodcastService) DeleteFeedFiles(ctx context.Context, feed *database.Pod
 	_ = os.Remove(filepath.Join(root, feedSlug(feed.Title, feed.ID)))
 }
 
+// AdminDeleteEpisodeFile (§0 item 8): ONE downloaded episode's file is
+// removed from disk and its row reset to pending (facts cleared,
+// file_path kept — fetch-maintained layout). Runs under the first-admin
+// identity (caller supplies the admin ctx — invariant 12). The poll
+// upsert never touches download_state, so the file stays deleted.
+func (s *PodcastService) AdminDeleteEpisodeFile(ctx context.Context, episodeID pgtype.UUID) error {
+	ep, err := s.db.GetPodcastEpisode(ctx, episodeID)
+	if err != nil {
+		return errNotFound("episode not found")
+	}
+	if !ep.SourceFeedID.Valid {
+		return fmt.Errorf("episode has no feed reference")
+	}
+	if ep.DownloadState != "downloaded" {
+		return nil // nothing on disk; idempotent no-op
+	}
+	feed, err := s.db.GetPodcastFeed(ctx, ep.SourceFeedID)
+	if err != nil {
+		return fmt.Errorf("feed lookup: %w", errNotFound("feed not found"))
+	}
+	root, err := s.downloadRootAbs(ctx, &feed)
+	if err != nil {
+		return err
+	}
+	if ep.FilePath != "" {
+		_ = os.Remove(filepath.Join(root, ep.FilePath))
+		base := filepath.Join(root, strings.TrimSuffix(ep.FilePath, filepath.Ext(ep.FilePath)))
+		_ = os.Remove(base + ".cover.jpg")
+	}
+	return s.db.ResetPodcastEpisodeFileDeleted(ctx, episodeID)
+}
+
+// AdminDeleteFeedFiles (§0 item 8): every DOWNLOADED episode of the
+// feed loses its disk file; rows reset to pending. Returns how many
+// rows were reset. Poll upsert never touches download_state → a
+// refresh re-lists metadata but does NOT re-materialize files.
+func (s *PodcastService) AdminDeleteFeedFiles(ctx context.Context, feedID pgtype.UUID) (int64, error) {
+	feed, err := s.db.GetPodcastFeed(ctx, feedID)
+	if err != nil {
+		return 0, errNotFound("feed not found")
+	}
+	eps, err := s.db.ListPodcastEpisodes(ctx, feedID)
+	if err != nil {
+		return 0, err
+	}
+	root, err := s.downloadRootAbs(ctx, &feed)
+	if err != nil {
+		return 0, err
+	}
+	for _, ep := range eps {
+		if ep.DownloadState != "downloaded" || ep.FilePath == "" {
+			continue
+		}
+		_ = os.Remove(filepath.Join(root, ep.FilePath))
+		base := filepath.Join(root, strings.TrimSuffix(ep.FilePath, filepath.Ext(ep.FilePath)))
+		_ = os.Remove(base + ".cover.jpg")
+	}
+	return s.db.ResetPodcastFeedFilesDeleted(ctx, feedID)
+}
+
 // downloadRootAbs resolves the podcasts library's single download root
 // (purpose='podcast') as an absolute filesystem path.
 func (s *PodcastService) downloadRootAbs(ctx context.Context, feed *database.PodcastFeeds) (string, error) {