feat: add remote trust and server identity pinning

- Add SSH-style server identity keys and known-host verification for remote serve endpoints.
- Add remote add/list/remove commands for explicit endpoint persistence.
- Fix remote clients listing to fan out through target discovery instead of ambiguous auto-routing.
- Add URL glob matching for tabs filter and count with extension tests.
- Add n8n credential pinning for server public keys or SHA256 fingerprints.
- Remove obsolete compat shim behavior while keeping empty compat seams for future protocol changes.
- Bump browser-cli to 0.16.4 and n8n node to 0.3.1.
- Cover known-hosts, remote registry, compat seams, n8n protocol verification, and URL matching with tests.

tests/test_serve.py

@@ -228,33 +228,6 @@ class TestAuthSuccess:
     client.close()
     t.join(timeout=2)
 
-  def test_uppercase_pubkey_normalized_by_compat(self, tmp_path, monkeypatch):
-    """Clients < 0.9.3 may send uppercase pubkeys; compat layer normalises before auth."""
-    path = tmp_path / "authorized_keys"
-    pem, pub = generate_keypair()  # pub is lowercase hex
-    path.write_text(pub + "\n")
-    key_path = tmp_path / "client.key.pem"
-    key_path.write_bytes(pem)
-    priv = load_private_key(key_path)
-
-    monkeypatch.setattr("browser_cli.client.targets.resolve_socket", _mock_no_browser)
-
-    client, server = _pair()
-    t = _spawn(server, path)
-
-    challenge = _recv_framed(client)
-    nonce = bytes.fromhex(challenge["nonce"])
-    # old client sends uppercase pubkey
-    msg = {"id": "x", "command": "tabs.list", "args": {}, "user_agent": "browser-cli/0.9.2", "pubkey": pub.upper()}
-    msg["sig"] = sign(priv, nonce, msg).hex()
-    _send_framed(client, json.dumps(msg).encode())
-    resp = _recv_framed(client)
-
-    assert "unauthorized" not in resp.get("error", "").lower()
-    assert "browser" in resp.get("error", "").lower() or "connected" in resp.get("error", "").lower()
-    client.close()
-    t.join(timeout=2)
-
   def test_post_quantum_kex_auth_reaches_proxy(self, tmp_path, monkeypatch):
     """ML-KEM shared secret is decapsulated and bound to the auth signature."""
     monkeypatch.setattr("browser_cli.client.targets.resolve_socket", _mock_no_browser)