Product Updates: Update-Awareness for Installed Products + Release Notes

[Wiesenwischer]

Goal

Make users aware that newer versions of installed products are available, and give them direct access to release notes before they upgrade.

Today, a product deployed at v1.0.2 keeps running silently even after v1.1.0 appears in the synced source. The user has no signal, no comparison, no release notes. This feature closes that gap.

Specification

See PLAN-product-updates.md.

Scope

• Track "latest available version" per product during source sync (SemVer-newer-only comparison).
• Extend product/stack YAML metadata with releaseNotesUrl and support an optional CHANGELOG.md convention next to stack files.
• On ProductDeploymentDetail: Update available badge next to the installed version + link to release notes / built-in release-notes viewer.
• Dashboard / product-deployments overview highlights deployments with available updates.
• One-time persistent notification per (deployment, latest-version) using the existing NotificationFactory dedup pattern (mirrors the RSGO self-update precedent in GetVersionHandler).
• Built-in release-notes viewer renders Markdown from CHANGELOG.md or linked URL (if same-origin / allowed host).

Out of scope: downgrade/"other-version" awareness, multi-version changelog diffing, Git-tag/GitHub Release API integration.

Tasks

• Catalog: track latest available version per product during source sync
• YAML schema: add releaseNotesUrl + document CHANGELOG.md convention
• Domain + Application: ProductUpdateAvailable notification type, factory helper, dedup by {productDeploymentId}:{latestVersion}
• API: endpoint for update status per product deployment + release-notes fetch
• UI (rsgo-generic): update badge, notification, dashboard indicator, release-notes viewer
• AMS UI counterpart (separate repo ReadyStackGo.Ams)
• Tests: unit (SemVer compare, dedup), integration (API), E2E (badge render)
• Documentation & Website (DE/EN), Roadmap update