Ignore expected upgrade nudges in Agent Feedback (#100840)
### What?
- Exclude intentional one-time `SecurityFatalError` and
`UpgradeNudgeError` upgrade stops from the private Agent Feedback
reporting protocol.
- Keep retries that remain blocked, or documented remediation that
fails, eligible as unexpected behavior.
- Add an Agent Feedback eval with one genuine documentation mismatch and
one expected upgrade stop. It requires the documentation report and
rejects any report for the expected stop.
- Add focused coverage for the internal protocol loader.
### Why?
The Next.js upgrade gate intentionally stops a successful command once,
explains that an upgrade is recommended, and allows the next run to
continue. Agents were treating that expected stop as a Next.js error and
filing duplicate feedback. The private reporting protocol should
distinguish the expected gate from an actual failure of the retry or
remediation path.
This does not change the public generated `AGENTS.md` instructions.
### Verification
| Check | Result |
| --- | --- |
| Agent Feedback CLI and protocol tests | 25 passed |
| Eval fixture/config validation | Passed |
| Prettier | Passed |
| Agent eval model run | Attempted twice with the rebuilt local package;
both shared AI Gateway requests failed before model execution |
