Add Electron 43 prebuild support

[davej]

Summary

• add Electron 43.2 and Electron 38.7 prebuild targets
• update native build tooling for Node 24 / Electron ABI 148
• modernize Linux, macOS, and Windows builders
• build RobotJS in ABI mode instead of the incorrect default Node-API mode
• clean generated prebuilds and fail CI unless every requested ABI-tagged binary is retained
• retain pull-request binaries as CI artifacts without publishing release assets

Verification

• loaded the generated arm64 ABI 148 binary directly in Electron 43.2.0
• macOS CI passes and retains 11 x64 plus 11 arm64 Mach-O binaries
• Linux CI passes and retains 11 x64 ELF binaries
• Windows CI passes and retains 11 x64 PE binaries
• every artifact contains ABI 148 and no untagged generic native binary

Coordinated work

• ToDesktop/todesktop-builder#540 upgrades Builder and its embedded Desktopify
• ToDesktop/todesktop#335 upgrades cloud packaging

This remains draft until the coordinated Electron 43 changes are ready to merge and version 0.6.28 can be published.

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
package.json	36% smaller
.github/workflows/build-mac.yml	31% smaller
.github/workflows/build-linux.yml	25% smaller
.github/workflows/build-windows.yml	24% smaller
package-lock.json	6% smaller
README.md	Unsupported file format
binding.gyp	Unsupported file format
scripts/clean-prebuilds.js	0% smaller
scripts/verify-prebuilds.js	0% smaller