chore: update electron-builder and signer publisherName

[Aerilym]

No description provided.

[Copilot]

Pull request overview

This PR updates the electron-builder package from an alpha version to a stable release and changes the Windows code signing publisher name from "Oxen Labs" to "Session Technology Foundation".

• Update electron-builder from version 26.0.0-alpha.8 to 26.0.12 (stable release)
• Move Windows publisherName configuration from top-level to signtoolOptions object
• Update all related electron-builder dependencies and their transitive dependencies

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
package.json	Updates electron-builder version and restructures Windows signing configuration to move publisherName into signtoolOptions object
yarn.lock	Updates electron-builder and all related dependencies (app-builder-lib, builder-util, dmg-builder, electron-publish), removes deprecated bluebird-lst dependency, adds new dependencies (plist, tiny-async-pool, semver), and cleans up uid fields from sharp-libvips entries

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