ostp-gui/package.json sets "type": "module", so a .js file is loaded as an ES
module and `require` is not defined — the installer build died on the first
line of stage-sidecar.js. Renamed to .cjs, which opts that one file back into
CommonJS.
The failure was also reported in the wrong place. pwsh does not abort a run
block when a native command exits non-zero, so the build carried on past the
dead script and failed several steps later complaining about a sidecar that
nothing had staged. The two commands are chained now, so staging failures
surface as themselves.
Verified locally this time: the script resolves the host triple, copies the
helper to the name Tauri expects, and warns about a missing wintun.dll rather
than failing silently.
