fix: update mempalace mcp command to use mempalace-mcp entry point

cmd_mcp() in cli.py was still printing `python -m mempalace.mcp_server`
as the setup command. Update to use the mempalace-mcp console entry
point added in the previous commit.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mempalace/cli.py

@@ -367,7 +367,7 @@ def cmd_instructions(args):
 
 def cmd_mcp(args):
     """Show how to wire MemPalace into MCP-capable hosts."""
-    base_server_cmd = "python -m mempalace.mcp_server"
+    base_server_cmd = "mempalace-mcp"
 
     if args.palace:
         resolved_palace = str(Path(args.palace).expanduser())