## Summary
Implements Spec 284 for provider-neutral artifact source taxonomy.
- add shared artifact source descriptor, resolver, taxonomy, and provider-detail support
- update findings, evidence snapshots, stored reports, inventory items, and tenant review surfaces to disclose descriptor-first artifact summaries
- add bounded Pest unit, feature, guard, and browser coverage for the taxonomy slice
- include the completed Spec 284 package artifacts under `specs/284-provider-neutral-artifact-source-taxonomy/`
## Notes
- branch: `284-provider-neutral-artifact-source-taxonomy`
- commit: `bf8d59e0`
- this PR was created as part of the requested commit/push/PR flow against `platform-dev`
Co-authored-by: Ahmed Darrazi <ahmed.darrazi@live.de>
Reviewed-on: #343
