Rename MCP server identifier from state-hub to dev-hub

Introduce canonical MCP_SERVER_NAME constants, shared registration helpers,
and a migrate_mcp_config.py script for ~/.claude.json upgrades. Registration,
patch, and custodian CLI checks accept both dev-hub and legacy state-hub during
transition. API root metadata and session-protocol template reflect the new name.

scripts/mcp_registration.py

@@ -0,0 +1,30 @@
+"""Helpers for ~/.claude.json MCP server registration checks."""
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+from mcp_server.constants import LEGACY_MCP_SERVER_NAME, MCP_SERVER_NAME
+
+
+def load_claude_json(path: Path | None = None) -> dict | None:
+    claude_json = path or Path.home() / ".claude.json"
+    if not claude_json.exists():
+        return None
+    return json.loads(claude_json.read_text())
+
+
+def mcp_server_registered(config: dict | None) -> bool:
+    if not config:
+        return False
+    servers = config.get("mcpServers", {})
+    return MCP_SERVER_NAME in servers or LEGACY_MCP_SERVER_NAME in servers
+
+
+def resolve_mcp_server_name(config: dict) -> str | None:
+    servers = config.get("mcpServers", {})
+    if MCP_SERVER_NAME in servers:
+        return MCP_SERVER_NAME
+    if LEGACY_MCP_SERVER_NAME in servers:
+        return LEGACY_MCP_SERVER_NAME
+    return None