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)

server/app.py

@@ -48,7 +48,10 @@ VERSION = _version()
 _CDN = {"state": "unknown", "kbps": 0.0, "ts": 0.0, "hist": []}
 # origin (primary provider pages/API) health — separate host, separate failure
 # mode (observed 2026-09-03: CDN fine while origin 503'd "Under Maintenance")
-_ORIGIN = {"state": "unknown", "msg": "", "ts": 0.0}
+_ORIGIN = {"state": "unknown", "msg": "", "ts": 0.0, "hist": []}
+# ponytail: fixed threshold; if the CDN's normal throughput drifts below it
+# the pill sits on "slow" — tune via ANIWEB_CDN_KBPS, not a percentile.
+_CDN_THRESHOLD = float(os.environ.get("ANIWEB_CDN_KBPS", "40"))
 
 
 def _cdn_probe():
@@ -81,7 +84,7 @@ def _cdn_probe():
             kbps = len(r.content) / 1024 / max(time.time() - t, 0.01)
         except Exception:
             kbps = 0.0
-        now = "OK" if kbps >= 40 else "DEGRADED"
+        now = "OK" if kbps >= _CDN_THRESHOLD else "DEGRADED"
         if now != state:
             print(f"[probe] CDN {now} ({kbps:.0f} KB/s)", flush=True)
         state = now
@@ -103,6 +106,8 @@ def _origin_probe():
         state, msg = "DOWN", str(e)
     prev = _ORIGIN["state"]
     _ORIGIN.update(state=state, msg=msg, ts=time.time())
+    _ORIGIN["hist"].append({"t": time.time(), "state": state})
+    del _ORIGIN["hist"][:-20]
     if state != prev:
         print(f"[probe] ORIGIN {state} ({msg})", flush=True)
 
@@ -114,7 +119,7 @@ threading.Thread(target=_cdn_probe, daemon=True).start()
 async def cdn_status():
     """CDN + origin health (read-only, public). Top-level fields are the CDN
     probe (existing shape); .origin is the anidb.app pages/API probe."""
-    return {**_CDN, "origin": _ORIGIN}
+    return {**_CDN, "threshold": _CDN_THRESHOLD, "origin": _ORIGIN}
 
 # ---------- auth: multi-user, signed cookies ----------
 users.migrate_legacy()  # file-based legacy import; db.init() absorbs its output