The coordinator can now ingest a dataset itself, not only accept client-supplied
chunk URIs.
- internal/chunk: a deterministic, generic TSV row splitter — repeats the header
per shard, buffers one shard at a time, rejects header-only input. Unit-tested.
- POST /jobs/upload (multipart): streams the dataset into an input artifact,
splits it into shard artifacts, and creates one shard task per shard, all in
one transaction; blobs are cleaned up if the transaction fails.
- GET /tasks/{id}/input streams a task's input shard back to the worker.
- domain: NewUploadedJob, NewShardTask, Task/Job.InputArtifactID; a shard task's
input is an artifact, not a URI. Claim response nests input:{uri,sha256} per
the contract, with uri = /tasks/{id}/input for shards.
- migration 0005 makes input_uri nullable and adds a has-input check.
- The existing URI-based POST /jobs path is untouched; both coexist.
Efremenko Arhip
c3243a6b7e