Add safe project close and Recycle Bin deletion

[WebCrew]

Summary

• add explicit Close and Delete controls to the project strip
• protect unsaved work before closing with Cancel, Discard, or Save & Continue
• move deleted projects to the operating system Recycle Bin after exact-name confirmation
• reject filesystem roots, protected user folders, and Parlyn application resources
• keep the active project session intact when validation or Recycle Bin operations fail
• version the candidate as 0.5.0-beta.4 so the Windows installer is named Parlyn-Engine-Setup-0.5.0-beta.4-x64.exe
• extend automated checks and the maintainer acceptance checklist

Local verification

• npm run check
• npm run build:renderer:release
• git diff --check

The real Electron preload smoke test is intentionally exercised by the Windows workflow; this Linux container cannot launch sandboxed Electron as root without a display.

Closes #27