status: consolidate the pill to one dot + one word; upgrade the panel

- pill: two host dots -> ONE consolidated state (down > slow > up) —
  the at-a-glance question is 'can I watch?', which is one state;
  per-host detail belongs in the tap panel
- panel: dashed slow-threshold line in the CDN sparkline (drawn at the
  server's real threshold, not a client copy) + origin up/down step
  sparkline so 'how long has the origin been down' is visible
- server: origin probe keeps a 20-sample hist like the CDN probe;
  DEGRADED threshold is now ANIWEB_CDN_KBPS (default 40) and is
  returned in /api/cdn so the UI draws the line at the live value
- tests: pill assertions switched to consolidated states; fixtures
  carry origin hist + threshold; assert both sparklines + threshold line
- docs: README + SPEC synced; preview on :8322 restarted (pid 44382)

README.md

@@ -61,9 +61,11 @@ proxy is the way in. See [SPEC.md](SPEC.md) for the rest.
 
   ![detail](docs/img/detail.png)
 
-- **Status** — the header pill shows upstream/CDN health (dots +
-  label); tap opens a panel with detail + the ~1h throughput trend.
-  A failure overlay names the CDN when it's the likely culprit.
+- **Status** — the header pill shows one consolidated state — up /
+  slow (KB/s) / down — as a single dot; tap opens a panel with the
+  per-host breakdown, the ~1h CDN trend (dashed slow-threshold line),
+  and origin up/down history. A failure overlay names the CDN when
+  it's the likely culprit.
 
 - **Stats** — `?stats`: watch minutes, episodes, streaks, sub/dub
   split, weekday/per-day heatmaps, top-10 shows, top searches