fix(electron): correct NSIS uninstaller $INSTDIR for 64-bit (#1055)

* chore(electron): add INSTDIR logging to uninstall for diagnostics

* fix(electron): correct INSTDIR in uninstaller for upgrade->uninstall path

electron-builder's un.onInit resolves $INSTDIR to Program Files (x86)
instead of Program Files during the upgrade->uninstall flow. Explicitly
read the 64-bit registry InstallLocation in customRemoveFiles to correct
the path before any file operations.

* 3.45.3

3.45.2

3.45.1

3.45.0

3.44.2

3.44.1

3.44.0

3.43.3

3.43.2

3.43.1