v0.260.0 — a box ahead of the catalog reads „Naprakész", and the pin never moves backwards (R-524)

MEASURED 2026-09-15 (BIGNIGHT Phase 6): privatebin updated 2.0.5 -> 2.0.6, catalog
reverted to 2.0.5, and the box read „Frissítés elérhető — ma" over an Update that
would have moved the pin BACKWARDS onto a possibly-migrated datadir.

- stacks.CatalogOrder: the comparison gains a fourth answer (Ahead) and moves out of
  web, so the badge and UpdatePreflight cannot drift apart.
- The badge: ahead reads „Naprakész"/"Up to date", tag-ok, with a title saying why.
- The refusal: UpdatePreflight returns `downgrade` (409), born as a bundle key; the
  API now renders update refusals through errText so it reaches English households.
- Ahead is narrow: every differing service must be orderable AND newer, else Behind.
- Ordering is util.Version.Compare behind a tag normaliser — no second comparator.
- Three red-proofs, each seen to fail.

R-589 was already fixed in v0.258.0; only its register row was stale.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/web/updatebadge_test.go

@@ -87,6 +87,14 @@ func TestGroupD_FourStates(t *testing.T) {
 			stack:     ubStack(map[string]stacks.InstalledImage{"web": rec("old:1"), "db": rec(tpl["db"])}, tpl, "2026-09-02"),
 			wantBadge: true, wantLabel: "Frissítés elérhető — ma", wantClass: "tag-warn",
 		},
+		{
+			// R-524, the BIGNIGHT case: the box updated and the catalog was reverted under it.
+			// It must NOT read „Frissítés elérhető" — the update behind that word is a downgrade.
+			name: "AHEAD of the catalog — up to date, not a warning",
+			stack: ubStack(map[string]stacks.InstalledImage{"web": rec("privatebin/pdo:2.0.6")},
+				map[string]string{"web": "privatebin/pdo:2.0.5"}, "2026-09-02"),
+			wantBadge: true, wantLabel: "Naprakész", wantClass: "tag-ok",
+		},
 		{
 			name:      "NO RECORD AT ALL (legacy app.yaml) — nothing rendered",
 			stack:     ubStack(nil, tpl, "2026-07-18"),