Warden checks failing for dependabot updates

[jamescrosswell]

Environment

• Workflow: getsentry/.github → .github/workflows/warden.yml (org-level Warden workflow)
• Action: getsentry/warden@v0
• Affected repo (example): getsentry/sentry-dotnet
• Trigger: pull_request events opened by dependabot[bot]
• Symptom scope: every open Dependabot PR in sentry-dotnet (and presumably any other getsentry/* repo whose Dependabot secret store is missing/misconfigured WARDEN_MODEL)

Steps to Reproduce

1. Open any Dependabot PR in a getsentry/* repo that uses the org-level Warden workflow — e.g. getsentry/sentry-dotnet#5253.
2. Wait for the Warden workflow to run.
3. Inspect the external check runs posted by warden.sentry.dev and the workflow logs at the Warden run.

Expected Result

Either:

• All Warden skill checks (warden: code-review, warden: find-bugs, warden: gha-security-review, warden: security-review) succeed on Dependabot PRs the same way they do on human-authored PRs (e.g. sentry-dotnet#5241, where all four are green); or
• If required secrets aren't available in the Dependabot secret scope, the check-permissions gate skips the warden job cleanly and the checks come back NEUTRAL/skipped — not FAILURE.

Actual Result

Three of the four Warden skill checks fail on every Dependabot PR with FAILURE:

• warden: code-review
• warden: find-bugs
• warden: gha-security-review

(warden: security-review passes, because it doesn't use the Pi runtime.)