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)

.gitignore

@@ -7,3 +7,4 @@ server.log
 server.pid
 pi-session-*.html
 .pytest_cache/
+server-*.log