Safe-outputs allowed-teams ignored and mentions sanitized because of wrong github token

## Summary

`safe-outputs.mentions.allowed-teams` works in **Process Safe Outputs** but fails during **Ingest agent output** (`collect_ndjson_output.cjs`). Mentions are backtick-escaped there with the default `GITHUB_TOKEN`, so by the time `add_comment` runs with the correct allowlist, the body is already `` `@user` `` and GitHub never notifies.

This is a follow-on to #42225 / #42313: that fix correctly honors pre-resolved aliases in `add_comment`, but an earlier sanitize path undoes it.

## Expected

When `safe-outputs.github-token` is set (PAT with `read:org`), both:

1. Ingest agent output (`collect_ndjson_output`), and
2. Process Safe Outputs / `add_comment`

should use that token to resolve `mentions.allowed-teams` and preserve raw `@login` mentions for team members.

## Actual

| Stage | Token | Team members | Mention form |
|---|---|---|---|
| Agent MCP / `safeoutputs.jsonl` | n/a | n/a | raw `@login` |
| **Ingest agent output** (`collect_ndjson`) | default `GITHUB_TOKEN` | **404** on `GET /orgs/.../teams/.../members` → allowlist collapses to dispatch actor only | body rewritten to `` `@login` `` |
| Process Safe Outputs / `add_comment` | `safe-outputs.github-token` | full team list (e.g. 31 members) | cannot unwrap already-backticked mentions → posted as `` `@login` `` |

Compiled lockfile pattern:

- **Ingest agent output**: no `github-token:` override → `GITHUB_TOKEN`
- **Process Safe Outputs**: `github-token: ${{ secrets.… }}` from `safe-outputs.github-token`

## Evidence (repro)

Private control-repo workflow with:

```yaml
safe-outputs:
github-token: ${{ secrets.MY_GH_TOKEN }} # PAT with read:org
mentions:
allowed-teams:
- my-org/my-team
add-comment:
# ...
```

Ingest logs:

```text
[MENTIONS] Fetching members for 1 configured team(s)
GET /orgs/my-org/teams/my-team/members → 404
[MENTIONS] Cannot access team my-org/my-team (HTTP 404)
[OUTPUT COLLECTOR] Allowed mentions:
```

Process Safe Outputs logs (same run): team fetch succeeds with the configured PAT; member is on the allowlist; posted comment still has `` `@member` `` because `agent_output.json` was already escaped at ingest.

Related: #42225 / #42313 (add_comment second-pass allowlist). Not caused by the `allow-team-members` → `allowed-collaborators` rename.

## Suggested fix

One of:

1. Wire `safe-outputs.github-token` into the **Ingest agent output** `actions/github-script` step (same as Process Safe Outputs), so `resolve_mentions_from_payload` can list team members before sanitizing; or
2. Defer mention sanitization until Process Safe Outputs / handlers (where the configured token already runs), and keep ingest as structural validation only.

Option 1 is the smaller behavioral change if ingest must keep sanitizing.