Adds an unsigned, manual-download update flow. The main process fetches the OSS
updates/releases.json manifest (DSH_UPDATE_URL overrides), compares the latest
version, and on startup and hourly prompts to open the per-platform installer
URL; a preload bridge exposes the same check to the SPA's About "check for
updates" button, which renders the version, notes, and a download link.
scripts/generate-release-json.mjs builds the manifest from the packaged
.dmg/.exe. Windows nsis packaging is configured.
Co-Authored-By: Claude <noreply@anthropic.com>
Pine