[Copilot]

AWF startup failures need actionable download diagnostics, and Windows-generated install steps must use the supported Bash shell. The installer already retries downloads and verifies checksums; this change adds regression coverage for those behaviors and platform-specific lock generation.

• Download diagnostics: Simulate a failed curl request and verify its underlying error is preserved in the installer output.
• Platform lock files: Verify generated Linux and Windows locks retain the checksum pin, and Windows selects Bash while Linux keeps its default shell.

- name: Install AWF binary
  shell: bash # Windows runner
  run: bash "${RUNNER_TEMP}/gh-aw/actions/install_awf_binary.sh" v0.28.62 --checksums-sha256 <digest>

• Fixes [AW Top 10] 05 Harden AWF binary installation startup step #76174