Add file and line lifecycle states with retry and reprocess controls #799

Summary

Introduce explicit lifecycle and operator controls for files and individual lines.

Proposed states

Files:

• Uploading
• Accepted
• Processing
• Completed
• CompletedWithErrors
• Failed
• Quarantined
• Cancelled

Lines:

• NotProcessed
• Processing
• Successful
• Rejected
• Failed
• RetryPending
• UnknownOutcome

Required behavior

• Persist state transitions and timestamps.
• Add configurable retry limits and backoff.
• Support file-level and line-level retry/reprocess commands.
• Support cancellation.
• Preserve failure details.
• Ensure completion means every line reached a terminal state.

Acceptance criteria

• Failed lines cannot remain indistinguishable from unprocessed lines.
• Operators can retry failed lines without re-running successful lines.
• Files with rejected or failed lines report CompletedWithErrors.
• Retry and cancellation operations are audited and idempotent.

Related issues

• #793 Keep failed transaction lines eligible for retry
• #796 Replace listening-directory handoff with durable file storage