web: a failure names itself on the page (issue #167)

The Series list row's fact line gains the failure word and its age in one
mark before the Notes chips, spelled through outcomeWord — the one
vocabulary shared with the Lanes chips. The detail page adds one sentence
beside the correction control while a Reader's number stands behind a
failure past the owner window, without naming the Reader. Each Lanes Site
name is a plain link to that Site's failing Series; the outcome chips stay
unlinked, and outcomeChips records why the promise is withdrawn.

backend/internal/web/admin_series.go

@@ -123,6 +123,11 @@ type seriesRowView struct {
 	// page, where a press that retires a Series from the Lane is on purpose
 	// and confirm-gated (issue #158).
 	Finished bool
+	// Failure names the standing failure and how long it has stood — "not
+	// found · 3d ago", "" while no failure row stands. Its own field, never a
+	// Notes chip: the chips cap at two plus a tail, so the one fact that
+	// names the failure would be the most likely to be truncated away.
+	Failure string
 }
 
 // adminSeries renders the filterable, bookmarkable Series list: filter, Site,
@@ -683,6 +688,9 @@ func seriesRow(a store.AdminSeries, i int, now time.Time) seriesRowView {
 		row.Ch = "—"
 	}
 	row.Age = checkedAge(now, a.LatestCheckedAt)
+	if a.FailureOutcome != "" {
+		row.Failure = outcomeWord(a.FailureOutcome) + " · " + checkedAge(now, a.FailingSince)
+	}
 	notes := seriesNotes(a, now)
 	if n := len(notes); n > 2 {
 		row.Notes, row.More = notes[:2], n-2
@@ -693,6 +701,20 @@ func seriesRow(a store.AdminSeries, i int, now time.Time) seriesRowView {
 	return row
 }
 
+// outcomeWord spells the wire failure word as the Lanes chips spell it — a
+// space, not the underscore: not_found reads "not found", no_chapter "no
+// chapter". The remaining words are their own spelling, so an unknown word
+// degrades to itself rather than vanishing from the page.
+func outcomeWord(wire string) string {
+	switch wire {
+	case "not_found":
+		return "not found"
+	case "no_chapter":
+		return "no chapter"
+	}
+	return wire
+}
+
 // seriesNotes are a row's hygiene chips in the design's order: no URL, no
 // cover, orphan, stale, reader sighting.
 func seriesNotes(a store.AdminSeries, now time.Time) []string {