[self-care:open-source-failures] Fix AW Optimization AI Credit Savings GitHub App token generation

`AW Optimization / AI Credit Savings` in `githubnext/gh-aw-cao` failed 4 times in the bounded seven-day snapshot while generating a GitHub App token, preventing the optimizer from starting useful work.

**Action:** CAO maintainers should inspect the workflow's GitHub App credential configuration and token-generation step inputs; accept when a new `AW Optimization / AI Credit Savings` run completes the `Generate GitHub App token` step successfully.

Critical findings:
- Representative failure: https://github.com/githubnext/gh-aw-cao/actions/runs/33939504516
- Affected workflow: `AW Optimization / AI Credit Savings`
- Evidence-supported cause: token generation failed before agent execution; the bounded snapshot does not distinguish misconfiguration from transient credential/service failure.
- Confidence: medium

Agent prompt

Review the `AW Optimization / AI Credit Savings` workflow and its shared actions to find why `Generate GitHub App token` is failing before agent execution. Check the app ID, private-key secret wiring, permission expectations, and any recent workflow or action changes affecting token generation. Make the smallest fix that restores token creation, and verify it by rerunning the workflow until the token-generation step passes.

Cluster evidence

Normalized signature: `Generate GitHub App token`

Representative runs:
- https://github.com/githubnext/gh-aw-cao/actions/runs/33939504516
- https://github.com/githubnext/gh-aw-cao/actions/runs/33939499260
- https://github.com/githubnext/gh-aw-cao/actions/runs/33939430558
- https://github.com/githubnext/gh-aw-cao/actions/runs/33939425563

Run count in bounded snapshot: 4
Severity: P1

### Control Plane
- Correlation ID: 33941632735-196
- Central repository: githubnext/gh-aw-cao
- Control-plane run: https://github.com/githubnext/gh-aw-cao/actions/runs/33941632735

> Generated by [SelfCare / Open Source Failures](https://github.com/githubnext/gh-aw-cao/actions/runs/33941816468) · pi · gpt54 · 19.9 AIC · ⌖ 8.46 AIC · ⊞ 8.3K · [◷](https://github.com/search?q=repo%3Agithubnext%2Fgh-aw-cao+is%3Aissue+%22gh-aw-workflow-call-id%3A+githubnext%2Fgh-aw-cao%2Fself-care-open-source-failures%22&type=issues)
> - [x] expires on Sep 19, 2026, 3:30 AM UTC

Start with the `AW Optimization / AI Credit Savings` workflow and the representative failed run, then inspect its shared actions and the `Generate GitHub App token` step inputs. Check the app ID, private-key secret wiring, permissions, and recent workflow or action changes. Done means a rerun completes token generation successfully before agent execution.

Written by the indexing model from the issue text.