ci: move smoke-test macOS + Windows legs to Blacksmith

Extends the smoke-test matrix migration:

  - macos-latest          -> blacksmith-6vcpu-macos-latest (drop-in,
    both Apple Silicon ARM64)
  - windows-latest        -> blacksmith-8vcpu-windows-2025 (Public
    Beta; bumps OS from Server 2022 to Server 2025). The Windows
    smoke test (apps/cli/tests/smoke-test-windows.ts) does not use
    Docker or WSL, so Blacksmith's "no Linux containers on Windows"
    caveat does not apply here.

macos-15-intel stays on GitHub-hosted -- Blacksmith macOS is ARM-only,
so the gating leg of the release pipeline cannot move yet.

Refs CLI-1501.

Author: claude

.github/workflows/release-shared.yml

@@ -101,7 +101,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        runner: [blacksmith-8vcpu-ubuntu-2404, macos-latest, macos-15-intel, windows-latest]
+        runner: [blacksmith-8vcpu-ubuntu-2404, blacksmith-6vcpu-macos-latest, macos-15-intel, blacksmith-8vcpu-windows-2025]
     runs-on: ${{ matrix.runner }}
     env:
       NPM_TAG: ${{ inputs.npm_tag }}