#21 MCP-2: MCP Submitter Tools

Implement hitl_list_policies, hitl_get_policy, hitl_request_decision, hitl_get_decision, hitl_cancel_decision, hitl_submit_context_update, hitl_list_reason_codes. Must require create/read permissions. hitl_request_decision must be non-blocking. (UB-MCP-3, UB-MCP-6, OP-MCP-1, UN-MCP-1)