Stop uploading the Windows signing runner npm cache

[enaboapps]

Windows releases spend most of their time saving the persistent signing runner’s global npm cache. In rc.20, the signed package built in 6 minutes, then compression and upload of the 6.7 GB cache took 42 minutes 40 seconds.

Remove the two setup-node npm cache inputs from the Windows release job. Node 24 and npm ci continue using the runner’s local cache without uploading it to GitHub.

Closes #979.

Validation

• Release workflow YAML parses successfully; diff check passed.
• The diff removes only the two cache inputs from the Windows signing job.
• Node 24.19.0: prediction-model, lint, tests (253 UI and 12 script tests), and build passed.
• Rust 1.97.1: fmt, clippy with warnings denied, and tests passed (634 unit tests, 2 ignored, 7 integration tests).
• Actual release timing must be confirmed on the next release; no release was triggered for this change.
• Independent review of head cd128404e960e3915c2658c74572cb344197b877 found no actionable findings and confirmed the runner's local npm cache remains available.
• All required GitHub CI checks passed on the independently reviewed head, including frontend, dependency audit, CodeQL, and macOS/Windows native packaging and integration checks.