#172: clear the empty-Site suppression row only for sidecar-down

Only sidecar-down ever writes a Site=='' row, so the loop's empty-Site
clear for the other three conditions was a no-op delete on every pass.
Move it out of the per-condition loop, scoped to ConditionSidecarDown.

backend/internal/latest/poller.go

@@ -647,12 +647,13 @@ func (p *Poller) ownerNotices(ctx context.Context, row store.LanePass) {
 				log.Printf("latest poll %s: clear owner notice: %v", row.Site, err)
 			}
 		}
-		// The site-wide conditions suppress under the empty Site; clear that
-		// row too, so a lifted sidecar-down fires again when it returns.
-		if !hasFault(faults, cond, "") {
-			if err := p.Store.ClearNotice(cond, ""); err != nil {
-				log.Printf("latest poll %s: clear owner notice: %v", row.Site, err)
 	}
+	// sidecar-down suppresses under the empty Site — one row across all
+	// browser Lanes (AC4) — so clear that row when it is absent from this
+	// pass's fault list, and a lifted sidecar fires again when it returns.
+	if !hasFault(faults, ConditionSidecarDown, "") {
+		if err := p.Store.ClearNotice(ConditionSidecarDown, ""); err != nil {
+			log.Printf("latest poll %s: clear owner notice: %v", row.Site, err)
 		}
 	}
 }