multi-account selection: --account-name hint, exit 3 NEEDS_HUMAN

onboard-driver.py accepts --account-name and forwards to muse-signin.py.
muse-signin.py detects Meta multi-account selection after OTP submit:
with a hint it clicks the matching display-name button (never the +1
collapsed entry); without a hint (or no match) it exits 3 so the queue
marks the job needs_human instead of stalling.

bin/muse-signin.py

@@ -58,6 +58,9 @@ def main():
                    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)')
+    p.add_argument('--account-name', default=None,
+                   help='display-name hint for Meta multi-account selection '
+                        '(never the "+1" entry)')
     args = p.parse_args()
 
     if args.cdp_port:
@@ -155,6 +158,41 @@ def main():
             print(f"SUCCESS: Logged in as {args.email} (title: {title})")
             ws.close()
             return 0
+        # Multi-account selection: Meta shows one button per matching
+        # account plus a "+1" collapsed entry. The "+1" is NOT a real
+        # account — click the button whose text contains the hinted
+        # display name. Without a hint (or no match), a human must pick.
+        if "Your email matches multiple accounts" in ev(
+                ws, "document.body.innerText.slice(0,2000)"):
+            if not args.account_name:
+                print("NEEDS_HUMAN: multiple accounts match and no "
+                      "--account-name hint was given", file=sys.stderr)
+                ws.close()
+                sys.exit(3)
+            picked = ev(ws, """(async()=>{
+              const want=%s.toLowerCase();
+              const btns=[...document.querySelectorAll('button')];
+              const t=btns.find(b=>b.innerText.toLowerCase().includes(want)
+                && !b.innerText.includes('+1'));
+              if(t){t.click();return true;} return false;
+            })()""" % json.dumps(args.account_name), True)
+            if not picked:
+                print(f"NEEDS_HUMAN: no account button matched "
+                      f"'{args.account_name}'", file=sys.stderr)
+                ws.close()
+                sys.exit(3)
+            print(f"Selected account '{args.account_name}', waiting...")
+            time.sleep(5)
+            body = ev(ws, "document.body.innerText.slice(0,200)")
+            if "Connected" in body or "Chats" in body:
+                print(f"SUCCESS: Logged in as {args.email} "
+                      f"(account: {args.account_name})")
+                ws.close()
+                return 0
+            print("WARNING: account selection did not land in chat",
+                  file=sys.stderr)
+            ws.close()
+            sys.exit(1)
         else:
             print(f"WARNING: Login may have failed. Title: {title}", file=sys.stderr)
             print(f"Body: {body[:100]}", file=sys.stderr)