propagation: single registry drives all node references

New bin/netvm-registry.py parses NODES.md (node -> cdp_port); every
consumer reads from it instead of hardcoding:
- onboard-driver.py: CDP_PORTS dict -> registry lookup (new nodes work)
- muse-signin.py: hardcoded 9410 -> --node/--cdp-port args
- muse-chat-api.py: hardcoded ACCOUNTS -> registry-built
- agent-health.sh: hardcoded muse/pip blocks -> loop over all active
  nodes (646 and opm now get health coverage too)
NODES.md: record opm node (9440).

bin/muse-signin.py

@@ -16,12 +16,25 @@ The operator then obtains the OTP (via chat with user) and re-runs:
 This keeps credentials out of the automation — the OTP is provided
 transiently via the operator, never stored.
 """
-import json, urllib.request, websocket, time, sys, argparse
+import json, urllib.request, websocket, time, sys, argparse, importlib.util
 
-CDP_URL = "http://127.0.0.1:9410/json/list"
+CDP_PORT_DEFAULT = 9410
 
-def get_page():
-    with urllib.request.urlopen(CDP_URL, timeout=5) as r:
+
+def _registry_port(node):
+    try:
+        path = "/home/super/Projects/NetVM/bin/netvm-registry.py"
+        spec = importlib.util.spec_from_file_location("netvm_registry", path)
+        mod = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(mod)
+        return mod.port_for(node)
+    except Exception:
+        return None
+
+
+def get_page(port):
+    cdp_url = "http://127.0.0.1:%s/json/list" % port
+    with urllib.request.urlopen(cdp_url, timeout=5) as r:
         ts = json.load(r)
     pages = [t for t in ts if t.get('type') == 'page']
     if not pages:
@@ -41,9 +54,20 @@ def main():
     p = argparse.ArgumentParser()
     p.add_argument('--email', required=True)
     p.add_argument('--otp', default=None)
+    p.add_argument('--node', default=None,
+                   help='node name: CDP port comes from the NODES.md registry')
+    p.add_argument('--cdp-port', default=None,
+                   help='explicit CDP port (overrides --node lookup)')
     args = p.parse_args()
 
-    page = get_page()
+    if args.cdp_port:
+        port = args.cdp_port
+    elif args.node:
+        port = _registry_port(args.node) or CDP_PORT_DEFAULT
+    else:
+        port = CDP_PORT_DEFAULT
+
+    page = get_page(port)
     ws = websocket.create_connection(page['webSocketDebuggerUrl'], timeout=15)
 
     # Step 1: Check if already logged in