MCP: serve tools from the API process over Streamable HTTP at /mcp

- netx_api/mcp_remote: ops / topology / bizMonitor tools, Bearer auth,
  per-tool RBAC filtering, ?groups= filter, readOnlyHint and group meta.
- Mount the official MCP Streamable HTTP app at /mcp (stateless);
  AuthAuditMiddleware is pure ASGI and skips /mcp.
- Let uvicorn chunk MCP responses; some Windows LSPs rewrite
  Content-Length replies on */mcp* paths into broken chunked framing.
- NETX_MCP_ALLOWED_HOSTS opts into DNS-rebinding checks (off by default
  so LAN and reverse-proxy hosts work; Bearer is the gate).
- Remove the three stdio Python MCP packages; tests moved to /mcp,
  including real-TCP framing regressions.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

netx_api/mcp_remote/topology/layout_ops/rings.py

@@ -0,0 +1,35 @@
+"""Ring/chain layout entry: dual-hub min-rings first, else UME petals.
+
+- ``min_rings``: two agg hubs + ≥2 parallel corridors → nested ellipse bands
+  (A1-ULU / PLAU↔ATP style). Prefer when structure says ``agg_bar``.
+- ``ume_petals``: rect-perimeter petals around AN anchors (legacy Sugiyama path).
+"""
+
+from __future__ import annotations
+
+from netx_api.mcp_remote.topology.layout_ops.min_rings import build_min_ring_skeleton
+from netx_api.mcp_remote.topology.layout_ops.state import LayoutParams, LayoutState, OpResult
+from netx_api.mcp_remote.topology.layout_ops.sugiyama import build_sugiyama_layout
+
+
+def build_ring_skeleton(state: LayoutState, params: LayoutParams | None = None) -> OpResult:
+    params = params or LayoutParams()
+    dual = build_min_ring_skeleton(state, params)
+    if dual is not None:
+        return OpResult(
+            state=dual.state,
+            moved=dual.moved,
+            op="build_ring_skeleton",
+            params={**(dual.params or {}), "mode": "min_rings"},
+            note=dual.note,
+        )
+    out = build_sugiyama_layout(state, params)
+    st = out.state
+    st.meta["rings_mode"] = st.meta.get("rings_mode") or "ume_petals"
+    return OpResult(
+        state=st,
+        moved=out.moved,
+        op="build_ring_skeleton",
+        params={**(out.params or {}), "mode": st.meta.get("rings_mode", "ume_petals")},
+        note=out.note or "UME petal rect-perimeter skeleton",
+    )