fix(nix): update Electron headers sha256 hash to fix hermes-desktop nix build (#72095)

[kyssta-exe]

Problem

nix/desktop.nix pins a stale sha256 for the Electron node-gyp headers tarball. Building hermes-desktop with Nix fails with:

hash mismatch in fixed-output derivation
specified: sha256-zi/QMwRZ0+FwE9XTE+DiSIeJXAwxmLKEaBWD5W3pMOI=
got:      sha256-zOl8rx6woWh7aeRUOlkTMviKc/EAQQX6nr/MxAx1ZPI=

Fix

Updated the pinned hash to the current correct value (the got: hash from the Nix error output).

Verification

• One-line change to nix/desktop.nix — Nix file, no Python tests to run.
• Visual diff confirms only the hash string changed.

Closes #72095

[teknium1]

Thanks for isolating the Electron-header failure.

Problems

• nix/desktop.nix:33-34 still pairs a URL derived from ${electron.version} with one fixed SHA. Replacing that SHA with the 41.9.1 value fixes only that version; it preserves the mismatch class whenever Electron changes.
• The PR does not change flake.lock, and current main has the same nix/desktop.nix blob as the PR base. The linked #61443/#53202 discussion records that the repository lock resolves Electron 41.0.2 while the proposed hash is for 41.9.1, so this can break the default locked build rather than support both inputs.

Suggested changes

• Remove the manual fetchurl/tar extraction and use ${electron.headers} as node-gyp's --nodedir, as in the durable approach documented on #61443.
• Verify both the pinned and overridden Electron inputs with nix build .#desktop.

Automated hermes-sweeper review.

[teknium1]

This hash is specific to the reported Electron 41.9.1 archive, while line 33 still derives the URL from arbitrary ${electron.version}. Please remove the independent fetch/hash and point node-gyp at ${electron.headers} instead; otherwise any differing or future Electron version can desynchronize this pair again.

[kyssta-exe]

Closing this PR because it is not mergeable: it has merge conflicts with main (GitHub reports mergeable=CONFLICTING / merge state DIRTY). Please rebase the branch onto the latest main and resolve the conflict in nix/desktop.nix, then this can be reopened for review. This is an automated close by the PR maintenance job (close-stale-duplicate-prs).