Simpler API for submitting SIPs for ingest, with configurable webhook in parameter, whitelisted

[006627]

Submitting a SIP through the API currently takes two calls: upload the file, then start a job to ingest it. This proposal adds a single call that does both, plus a webhook parameter, building on the notification-by-email/file/HTTP capability the ingest plugin already has.

The webhook parameter only accepts a URL that's on an admin-configured list of allowed destinations and that doesn't resolve to an internal address. This whitelist requirement applies only to this new endpoint's webhook parameter; the existing way of setting a job completion callback keeps working exactly as it does today, unchanged.

Acceptance Criteria

• A single API call accepts a SIP file and starts ingest, without a separate upload step first.
• That call accepts a webhook URL as a normal, documented parameter.
• RODA calls the given webhook URL when the ingest job finishes.
• A webhook URL is only accepted if it's on an admin-configured list of allowed destinations, and only if it doesn't resolve to an internal/private address; a submission with a disallowed or unsafe URL is rejected immediately, not accepted and silently failed later.
• The endpoint can be called by an external system using an API access token, without a browser session.

Notes

Authentication needs no new work: RODA's personal access tokens already authenticate any API call, including a new one, without a browser session.

Whether a submitted SIP still needs manual review or is accepted automatically depends on the parameters sent with the request, same as it does today for a job created the regular way.

Open Questions

• Should the webhook call require an acknowledgment from the receiver to be considered delivered, or is a successful response to the call enough, as it is today?
• Should large SIPs be uploadable in chunks through this new endpoint, or is a single upload (no size limit, no resume) good enough for now?

Out of Scope

• Uploading large files in chunks (see open questions).
• Any change to the existing upload/ingest screens in the web interface.