ServeFileByID and DownloadFile duplicated the lookup failure mapping and
each used an unchecked *strconv.NumError assertion that cannot match a
wrapped error. One helper now classifies 404 vs 400 via errors.As; each
endpoint keeps its own fallback for unclassified failures. ErrInvalidUploadID
became unused once both sites report ErrInvalidFileID for a malformed ID.
- Purify core micro-kernel by removing context hardcoded helpers and reverse dependencies
- Eliminate init() side effects in infra plugins with reversible lifecycle disposal
- Completely isolate plugins by removing cross-plugin imports and using core/contracts
- Introduce TaskService and RiskControlService contracts for unified cross-plugin APIs
- Regenerate Swagger documentation and update developer guide matrix
- Achieve 0 violations in check_cordis_architecture.sh and 100% test pass
ryan