Egress policies for raw-TCP traffic

Decisions to be made:

- [ ] Should we allow Substrate admin to configure how raw-TCP egress traffic should be handled?
- [ ] Are there any needs to do credential injections for raw-TCP egress traffic?

No files or tests are referenced in the issue body. Start by finding where raw-TCP egress traffic is implemented and where admin policy configuration is parsed, then read nearby docs/comments to understand expected behavior. Check any existing egress/credential handling paths before proposing a decision. Done when the issue is converted into a concrete, actionable specification for admin-configurable raw-TCP policy and credential injection requirements.

索引モデルが issue の本文から書いたものです。