Publish Windows preview downloads

[itsDNNS]

Summary

• adds a visible Windows Preview path from the repository landing page to the latest public release
• keeps checksum verification available as an optional, case-insensitive integrity check without making PowerShell part of the normal path
• uploads exact versioned Windows asset names and verifies the expected ZIP and checksum after release publication
• fails closed on release lookup errors and rejects duplicate or stale Windows Preview assets while preserving unrelated release files
• clarifies that workflow artifacts are CI evidence and release assets are the user download channel

Validation

• uv run pytest -q --ignore=tests/e2e: 3035 passed, 1 skipped
• focused Windows, documentation, workflow, and release contracts: 73 passed
• core locale validation: 69 language files in sync
• workflow YAML parse and Bash syntax validation
• git diff --check
• latest release and its current Windows Preview ZIP and checksum return HTTP 200 without authentication