Add GitHub App token generation to release workflow

[pethers]

Added steps to generate and use a GitHub App token for authentication in the release workflow.

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Checklist

• Tests pass locally (npm run test:unit, npm run test:integration).
• No new lint or knip errors (npm run lint, npm run knip).
• Documentation updated (README, INTEGRATION_TESTING.md, CONTRIBUTING.md, JSDoc) where behaviour changed.

OSINT changes only

Tick both boxes when any file under tests/integration/osint/__snapshots__/ or tests/fixtures/osint/ is modified by this PR:

• OSINT snapshot refresh acknowledged. I have reviewed every diff under tests/integration/osint/__snapshots__/, confirmed the methodology change is intentional, and regenerated the snapshots with npm run test:osint:snapshots -- -u.
• Methodology change documented. The justification for the scoring/classification/attribution change is described in this PR's body and (where appropriate) in INTEGRATION_TESTING.md § "OSINT QA Harness — Golden Snapshots".

See CONTRIBUTING.md § "Refreshing OSINT golden snapshots" for the full procedure and reviewer guidance.