Self-Driving Eval: Add UI for iteration

[AkhileshNegi]

Is your feature request related to a problem?
The v2 self-driving eval currently lacks a UI for starting or monitoring the prompt iteration loop, making it an API-only feature. This limits user accessibility and understanding of the process.

Describe the solution you'd like

• Add a "Run iteration loop" entry point: dataset_id, experiment_name, config_id, config_version, max_rounds
• Handle the 202 response with EvaluationIterationRunImmediatePublic details (iteration_run_id, status)
• Implement a webhook receiver for the EvaluationIterationReportPublic callback, aligned with the prompt-improvement pattern
• Display round-by-round history, the best round, and terminal stop_reason values (ceiling_reached, max_rounds_reached, round_failed)

Original issue

Is your feature request related to a problem?
v2 ships a self-driving eval → improve-prompt → eval loop (POST /api/v2/evaluations/iterations). There is no way to start one or watch it from the console, so the feature is API-only today.

Describe the solution you'd like

• Add a "Run iteration loop" entry point: dataset_id, experiment_name, config_id, config_version, max_rounds
• Handle the 202 response and its EvaluationIterationRunImmediatePublic handle (iteration_run_id, status)
• Add a webhook receiver for the EvaluationIterationReportPublic callback, following the prompt-improvement pattern
• Show round-by-round history, the best round, and the terminal stop_reason (ceiling_reached, max_rounds_reached, round_failed)

Comments: Stop-score is the mean of Adherence to Ground Truth and Adherence to Prompt; Knowledge Base is recorded per round for visibility only — worth reflecting in the UI so the numbers aren't confusing.

Parent: #265