Ingests one or more documents, normalizes content (extracting email container attachments if applicable), persists the initial submission state, and concurrently dispatches all active verification checks.

Execution Pipeline:

1. Tenant Resolution: Resolves tenant alias from authorizer context or the X-Tenant-Alias header.
2. Document Normalization:
   • Accepts base64 encoded bytes (image), remote URLs (url), or pre-staged S3 references (fileIdentifier).
   • Email containers (.eml, .msg) are parsed: the email message body is converted to a PDF document, and any valid image/PDF attachments are extracted as distinct verifiable documents.
3. Check Resolution:
   • If checks is provided, executes the specified checks.
   • If checks is omitted or empty, loads the tenant's default check configuration from verify-settings.
4. Concurrent Dispatch: Checks are submitted concurrently to their respective downstream engines.
5. Response: Returns submissionId and synchronous dispatch statuses (SUBMITTED or ERROR) along with the downstream apiUrl for polling.