fix(video): Remove stored analysis URL field

[HU-Lee]

Summary

• Remove unused url from YoutubeAnalysisResult so data-process matches the migrated analysis_result JSON shape.

Implementation notes

• Party/video matching already uses score and partyData, not url.

Evidence

• austincli agent check PASS, stack go-workflow, changed files 1, failures none.

Production checklist

• Deploy after the ba-analyzer migration/backend rollout. This change is compatible with migrated rows where analysis_result.url has been removed.