Seed / data migration command

[seanmalbert]

• General
• Backend
• Public
• Partners

Background / Issue

Existing static translation and content files (and any existing translations blob rows) must be
moved into the new key-level tables once per environment, idempotently, including converting
markdown bodies to HTML.

Technical Context

• TDD: §7.1.
• A script-runner command that: explodes existing translations blobs into per-key rows; loads
  base and per-site overrides into key rows (Partners overrides as global null-jurisdiction rows)
  with sourceHash baselines; extracts structured content into JurisdictionContent, converting
  markdown bodies to sanitized HTML. Idempotent, with a dry-run flag.
• Depends on: Key-level translation data model and migrations #6508; HTML sanitization for rich-text content #6513

Acceptance Criteria

• Re-running upserts rather than duplicates; a dry-run reports changes without writing.
• Base and public/Partners overrides land in the correct key rows; non-English rows carry a
  sourceHash of their English source.
• Markdown content bodies are converted to sanitized HTML and open cleanly in the editor; the
  dry-run report lists each converted body.

QA Notes

Backend. Run the dry-run and confirm the reported changes; run for real and confirm idempotency on a
second run. Spot-check converted markdown bodies render correctly and open in Tiptap.