chore: bump electron 42 header version for msvc compatibility

[deepak1556]

Followup to #316661

Bump only npm target to 42.3.0 that contains electron/electron@0e1fe29

The current preinstall header patching doesn't work for root node_modules due to order of lifecycle script invocation.

[Copilot]

Pull request overview

Follow-up to the Electron 42 update (PR #316661). Instead of preinstall-time patching of the cppgc/heap.h header (which didn't run early enough for root node_modules), this PR bumps the Electron headers npm target to 42.3.0, which already contains the MSVC-compatible upstream fix, and removes the custom header patching machinery.

Changes:

• Bump .npmrc headers target from 42.2.0 to 42.3.0 and hardcode the Electron runtime version in build/lib/electron.ts to 42.2.0.
• Remove the local cppgc/heap.h custom header and the related explanatory comment in build/npm/preinstall.ts.
• Drop the now-unnecessary explicit node build/npm/preinstall.ts invocation from all Windows CI pipelines and the PR workflow; bump build/.cachesalt.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.npmrc	Bumps Electron headers target to 42.3.0.
build/lib/electron.ts	Decouples headers target from runtime by hardcoding electronVersion = '42.2.0'.
build/npm/preinstall.ts	Drops the comment referencing the removed cppgc/heap.h patch.
build/npm/gyp/custom-headers/cppgc/heap.h	Deletes the custom MSVC-compatible header now obsoleted by 42.3.0.
build/azure-pipelines/win32/steps/product-build-win32-compile.yml	Removes explicit pre-install header-patch step.
build/azure-pipelines/win32/sdl-scan-win32.yml	Removes explicit pre-install header-patch step.
build/azure-pipelines/win32/product-build-win32-node-modules.yml	Removes explicit pre-install header-patch step.
.github/workflows/pr-node-modules.yml	Removes explicit pre-install header-patch step.
build/.cachesalt	Bumps cache salt to invalidate caches built against the prior header set.